Text generation

LocalAI generates text with the llama-cpp backend and with other backends, such as vllm and transformers. See also the Model compatibility for an up-to-date list of the supported model families.

Note:

• You can also specify the model name as part of the OpenAI token.
• If only one model is available, the API will use it for all the requests.

API Reference

Chat completions

https://platform.openai.com/docs/api-reference/chat

For example, to generate a chat completion, you can send a POST request to the /v1/chat/completions endpoint with the instruction as the request body:

curl http://localhost:8080/v1/chat/completions -H "Content-Type: application/json" -d '{
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "messages": [{"role": "user", "content": "Say this is a test!"}],
  "temperature": 0.7
}'

Available additional parameters: top_p, top_k, max_tokens

When a request omits max_tokens, the vLLM and SGLang backends do not cap generation at 200 tokens. Generation is bounded only by the context window of the model.

Reasoning models return their thinking in the reasoning field. When a model reasons and calls a tool in the same turn, see Interleaved Thinking with Tool Calls.

When stream: true is set and the llama.cpp backend fails before the first chunk, for example because the prompt exceeds the context size, the request fails with an HTTP error. The error message is not streamed as assistant content. An error after streaming has started is reported inside the stream.

Edit completions

https://platform.openai.com/docs/api-reference/edits

To generate an edit completion you can send a POST request to the /v1/edits endpoint with the instruction as the request body:

curl http://localhost:8080/v1/edits -H "Content-Type: application/json" -d '{
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "instruction": "rephrase",
  "input": "Black cat jumped out of the window",
  "temperature": 0.7
}'

Available additional parameters: top_p, top_k, max_tokens.

Completions

https://platform.openai.com/docs/api-reference/completions

To generate a completion, you can send a POST request to the /v1/completions endpoint with the instruction as per the request body:

curl http://localhost:8080/v1/completions -H "Content-Type: application/json" -d '{
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "prompt": "A long time ago in a galaxy far, far away",
  "temperature": 0.7
}'

Available additional parameters: top_p, top_k, max_tokens

List models

You can list all the models available with:

curl http://localhost:8080/v1/models

Anthropic Messages API

LocalAI supports the Anthropic Messages API, which is compatible with Claude clients. This endpoint provides a structured way to send messages and receive responses, with support for tools, streaming, and multimodal content.

Endpoint: POST /v1/messages or POST /messages

Reference: https://docs.anthropic.com/claude/reference/messages_post

Basic Usage

curl http://localhost:8080/v1/messages \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Say this is a test!"}
    ]
  }'

Request Parameters

Message Format

Messages can contain text or structured content blocks:

curl http://localhost:8080/v1/messages \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "max_tokens": 1024,
    "messages": [
      {
        "role": "user",
        "content": [
          {
            "type": "text",
            "text": "What is in this image?"
          },
          {
            "type": "image",
            "source": {
              "type": "base64",
              "media_type": "image/jpeg",
              "data": "base64_encoded_image_data"
            }
          }
        ]
      }
    ]
  }'

Tool Calling

The Anthropic API supports function calling through tools:

curl http://localhost:8080/v1/messages \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "max_tokens": 1024,
    "tools": [
      {
        "name": "get_weather",
        "description": "Get the current weather",
        "input_schema": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state"
            }
          },
          "required": ["location"]
        }
      }
    ],
    "tool_choice": {"type": "auto"},
    "messages": [
      {"role": "user", "content": "What is the weather in San Francisco?"}
    ]
  }'

Streaming

Enable streaming responses by setting stream: true:

curl http://localhost:8080/v1/messages \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "max_tokens": 1024,
    "stream": true,
    "messages": [
      {"role": "user", "content": "Tell me a story"}
    ]
  }'

Streaming responses use Server-Sent Events (SSE) format with event types: message_start, content_block_start, content_block_delta, content_block_stop, message_delta, and message_stop.

Response Format

{
  "id": "msg_abc123",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "This is a test!"
    }
  ],
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 10,
    "output_tokens": 5
  }
}

stop_reason is end_turn, tool_use, or max_tokens when the reply used up max_tokens.

Open Responses API

LocalAI supports the Open Responses API specification, which provides a standardized interface for AI model interactions with support for background processing, streaming, tool calling, and advanced features like reasoning.

Endpoint: POST /v1/responses or POST /responses

Reference: https://www.openresponses.org/specification

Basic Usage

curl http://localhost:8080/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "input": "Say this is a test!",
    "max_output_tokens": 1024
  }'

Reuse assistant messages

When you manage conversation history in your client, append assistant messages from a response’s output array to the next request’s input. Keep their content type as output_text. Use input_text for new user messages. Include earlier conversation items that the model still needs.

For example, submit this body to POST /v1/responses:

{
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "input": [
    {
      "type": "message",
      "role": "user",
      "content": [{"type": "input_text", "text": "What is the capital of France?"}]
    },
    {
      "type": "message",
      "role": "assistant",
      "content": [{"type": "output_text", "text": "Paris is the capital of France."}]
    },
    {
      "type": "message",
      "role": "user",
      "content": [{"type": "input_text", "text": "Which river flows through it?"}]
    }
  ]
}

WebSocket Responses

Connect to ws://localhost:8080/v1/responses (or wss:// when TLS is enabled) and send response.create messages over the WebSocket. Only one response may be in progress on a connection. Wait for response.completed or response.failed for the active response before sending the next response.create. An error that rejects an invalid or additional response.create applies only to that rejected message; it does not terminate a response that is already in progress.

Set the WebSocket-only generate field to false to prepare a request without running inference:

{
  "type": "response.create",
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "generate": false,
  "store": false,
  "input": "Say this is a test!"
}

LocalAI emits response.created followed by response.completed with no generated output. The completed response still has an ID that can continue the prepared request:

{
  "type": "response.create",
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "store": false,
  "previous_response_id": "resp_abc123",
  "input": []
}

Response IDs created with store: false are available only on the WebSocket connection that created them and are removed when that connection closes. A previous_response_id chain can contain multiple responses; LocalAI replays the complete conversation from the oldest response through the referenced response before appending the new input. The replay includes server-side MCP tool calls and their results, which are stored as function_call and function_call_output output items. Keep store: false for every descendant of a connection-local response. LocalAI rejects a store: true response that depends on connection-local history because the resulting stored chain would be broken after the WebSocket closes.

After delivery, LocalAI discards buffered stream events for store: false responses but retains their request and final response for continuation. A connection admits at most 128 local responses and accepts a new local request only while its current serialized history plus that request is at most 64 MiB. When either admission threshold is reached, LocalAI returns connection_store_limit_reached; reconnect to start a new local history. With authentication enabled, globally stored response IDs can be continued only by the identity that created them.

Request Parameters

Input Format

Input can be a simple string or an array of structured items:

curl http://localhost:8080/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "input": [
      {
        "type": "message",
        "role": "user",
        "content": "What is the weather?"
      }
    ],
    "max_output_tokens": 1024
  }'

Streaming responses

Set "stream": true to receive Server-Sent Events. Each response.output_item.added event assigns an output_index to an item. Use that index and the item ID to associate later deltas and completion events with the same item.

If a request without explicit tools produces reasoning, the stream uses separate items for reasoning and answer text. Each item keeps its original index throughout the stream. The response.completed event includes both items in the same index order, followed by any automatically parsed tool calls.

Background Processing

Run requests in the background for long-running tasks:

curl http://localhost:8080/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "input": "Generate a long story",
    "max_output_tokens": 4096,
    "background": true
  }'

The response will include a response ID that can be used to poll for completion:

{
  "id": "resp_abc123",
  "object": "response",
  "status": "in_progress",
  "created_at": 1234567890
}

Retrieving Background Responses

Use the GET endpoint to retrieve background responses:

# Get response by ID
curl http://localhost:8080/v1/responses/resp_abc123

# Resume streaming with query parameters
curl "http://localhost:8080/v1/responses/resp_abc123?stream=true&starting_after=10"

Canceling Background Responses

Cancel a background response that’s still in progress:

curl -X POST http://localhost:8080/v1/responses/resp_abc123/cancel

Multiple Replicas (Distributed Mode)

In distributed mode LocalAI replicates response metadata across frontend replicas, so retrieval, previous_response_id chaining and cancellation work regardless of which replica the load balancer picks:

• GET /v1/responses/{id} returns the response from any replica.
• POST /v1/responses/{id}/cancel is delegated over NATS to the replica that is actually generating, so generation really stops. If that replica is gone, the response is reported as cancelled without blocking.
• Streaming resume (?stream=true&starting_after=N) works on any replica, because the event buffer is read from the database (see Durable Storage below). Without a database (it always exists in distributed mode, so this only concerns a build that cannot reach it) the buffer is in the memory of the replica that generates, and a resume that reaches another replica returns HTTP 409 naming the owning replica.

State mode (see the distributed-state rules): the response metadata is shared state, a SyncedMap with a database Store. The table is the source of truth, a replica that starts later loads the newest rows (up to 10000), and changes reach the other replicas as deltas over NATS. The events are not sent over NATS: every replica reads them from the table. The generation itself, and its cancel function, live on one replica, the owner of the response; a cancel reaches it over NATS and through the cancel_requested flag.

Durable Storage

When LocalAI has a database (authentication enabled, or distributed mode), stored responses and the events of a background run are kept in two tables, open_responses and open_response_events. Without a database the store stays in memory, as before, and ends with the process.

With the tables:

• A response and its event buffer outlive a restart. GET /v1/responses/{id}, previous_response_id chaining and ?stream=true&starting_after=N read the tables, so any replica serves them and they work after a restart.
• The owner writes events in batches: at once for any event that is not a .delta event, and for deltas every 250 ms or 64 events. If the process dies, the deltas of the last 250 ms are lost.
• The buffer keeps the same caps as the memory store (8192 events and 64 MiB per response, oldest first). A resume below the oldest kept event returns HTTP 409 (ErrOffsetLost).
• Every read still checks the owner of the response: a caller who did not create it gets 404. An item_reference finds only an item of a response the caller created; the item of another user’s response is “not found”.
• Rows expire after OPEN_RESPONSES_STORE_TTL. With the TTL at 0 a database store applies a default of 7 days, because a table does not end with the process.

A running background response holds a lease in its row, which its owner renews every 15 seconds (the lease lasts 45 seconds). When the owner dies, for example because the pod is replaced, the lease runs out and the response is ended as failed with the error code server_restarted. A final response.failed event is added, so a client that resumes the stream gets every kept event and then the end. LocalAI does not run the request again: a generation cannot continue from a cut point, and tools may have had effects. Send the request again, with previous_response_id to keep the context. A standalone server ends the runs a previous process left when it starts. In distributed mode one frontend at a time runs the sweep.

POST /v1/responses/{id}/cancel sets a cancel_requested flag in the row. The owner checks it on every lease renewal, so a cancel works even if the bus message is lost. If the owner died before it could stop, the response ends as cancelled.

Tool Calling

Open Responses API supports function calling with tools:

curl http://localhost:8080/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "input": "What is the weather in San Francisco?",
    "tools": [
      {
        "type": "function",
        "name": "get_weather",
        "description": "Get the current weather",
        "parameters": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state"
            }
          },
          "required": ["location"]
        }
      }
    ],
    "tool_choice": "auto",
    "max_output_tokens": 1024
  }'

For streaming requests with JSON tool output, LocalAI waits for the complete JSON object before emitting a completed function_call item. Arguments can span multiple tokens. Read the arguments from the response.output_item.done event before executing the tool.

Reasoning Configuration

Configure reasoning effort and summary style:

curl http://localhost:8080/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ggml-koala-7b-model-q4_0-r2.bin",
    "input": "Solve this complex problem step by step",
    "reasoning": {
      "effort": "high",
      "summary": "detailed"
    },
    "max_output_tokens": 2048
  }'

Response Format

{
  "id": "resp_abc123",
  "object": "response",
  "created_at": 1234567890,
  "completed_at": 1234567895,
  "status": "completed",
  "model": "ggml-koala-7b-model-q4_0-r2.bin",
  "output": [
    {
      "type": "message",
      "id": "msg_001",
      "role": "assistant",
      "content": [
        {
          "type": "output_text",
          "text": "This is a test!",
          "annotations": [],
          "logprobs": []
        }
      ],
      "status": "completed"
    }
  ],
  "error": null,
  "incomplete_details": null,
  "temperature": 0.7,
  "top_p": 1.0,
  "presence_penalty": 0.0,
  "frequency_penalty": 0.0,
  "usage": {
    "input_tokens": 10,
    "output_tokens": 5,
    "total_tokens": 15,
    "input_tokens_details": {
      "cached_tokens": 0
    },
    "output_tokens_details": {
      "reasoning_tokens": 0
    }
  }
}

Backends

RWKV

RWKV support is available through llama.cpp (see below)

llama.cpp

llama.cpp is a popular port of Facebook’s LLaMA model in C/C++.

Features

The llama.cpp model supports the following features:

• 📖 Text generation (GPT)
• 🧠 Embeddings
• 🔥 OpenAI functions
• ✍️ Constrained grammars

Setup

LocalAI supports llama.cpp models out of the box. You can use the llama.cpp model in the same way as any other model.

Manual setup

It is sufficient to copy the ggml or gguf model files in the models folder. You can refer to the model in the model parameter in the API calls.

You can optionally create an associated YAML model config file to tune the model’s parameters or apply a template to the prompt.

Prompt templates are useful for models that are fine-tuned towards a specific prompt.

With the llama.cpp backend, streaming and non-streaming chat requests preserve the template’s grammar, stop strings, and message boundaries.

Automatic setup

LocalAI supports model galleries which are indexes of models. For instance, the huggingface gallery contains a large curated index of models from the huggingface model hub for ggml or gguf models.

For instance, if you have the galleries enabled and LocalAI already running, you can just start chatting with models in huggingface by running:

curl http://localhost:8080/v1/chat/completions -H "Content-Type: application/json" -d '{
     "model": "TheBloke/WizardLM-13B-V1.2-GGML/wizardlm-13b-v1.2.ggmlv3.q2_K.bin",
     "messages": [{"role": "user", "content": "Say this is a test!"}],
     "temperature": 0.1
   }'

LocalAI will automatically download and configure the model in the model directory.

Models can be also preloaded or downloaded on demand. To learn about model galleries, check out the model gallery documentation.

YAML configuration

To use the llama.cpp backend, specify llama-cpp as the backend in the YAML file:

name: llama
backend: llama-cpp
parameters:
  # Relative to the models path
  model: file.gguf

Backend Options

The llama.cpp backend supports additional configuration options that can be specified in the options field of your model YAML configuration. These options allow fine-tuning of the backend behavior:

Example configuration with options:

name: llama-model
backend: llama
parameters:
  model: model.gguf
options:
  - use_jinja:true
  - context_shift:true
  - cache_ram:4096
  - parallel:2
  - devices:CUDA1,CUDA2,CUDA3
  - fit_params:true
  - fit_target:1024
  - slot_prompt_similarity:0.5

Note: The parallel option can also be set via the LLAMACPP_PARALLEL environment variable, and grpc_servers can be set via the LLAMACPP_GRPC_SERVERS environment variable. Options specified in the YAML file take precedence over environment variables.

An explicit parallel: 1 (or n_parallel: 1) in the model options takes precedence over LLAMACPP_PARALLEL, like any other value. The environment variable is only used when neither option is set; if it is missing or not a number, the backend uses one slot.

Hardware auto-tuning (and how to override it)

On a detected GPU, LocalAI fills a few performance-relevant defaults the model config leaves unset - a larger physical batch on NVIDIA Blackwell, and a VRAM-scaled parallel slot count for concurrent serving. Both are gated on per-device VRAM at the model’s context: when a large context already fills a single card (e.g. a 27B model with a 200k context across 2×16 GiB), the batch boost and the extra parallel slots are suppressed so they can’t tip the tighter GPU into CUDA out-of-memory.

Anything you set explicitly in the model YAML always wins, so to pin a value just set it (e.g. batch: 512 or options: ["parallel:1"]). The effective values are logged at INFO when a model loads (effective runtime tuning …). To turn the hardware auto-tuning off entirely and run llama.cpp’s stock behavior, set:

LOCALAI_DISABLE_HARDWARE_DEFAULTS=true

Server-side prompt cache (repeated system prompts)

Agents, coding assistants, and Anthropic/OpenAI-compatible CLIs typically resend the same large system prompt on every turn. The llama.cpp server can short-circuit prefill for the matching prefix by stashing idle slot KV states in host RAM and reloading them on a hit. Three settings interact:

All three are on by default since LocalAI v4.3, so the prompt cache works out of the box for the common single-slot setup. If you’re on an older release, or you’ve explicitly disabled one of them, add the following to recover the behaviour:

options:
  - cache_ram:4096       # or -1 for no limit
  - kv_unified:true
  - cache_idle_slots:true

Set cache_ram:0 to opt out of the prompt cache entirely (saves host RAM at the cost of re-prefilling repeated prompts).

cache_ram:-1 removes the limit. With idle-slot saving on, every distinct prompt then leaves its slot state in host RAM, so a workload with many different prompts (classification, ingestion) grows the backend by roughly the KV size of each prompt until the host runs out of memory.

Saving and restoring a prompt cache

The server-side prompt cache lives in RAM and is lost when the model unloads. To keep the prompt state of one slot on disk, set slot_save_path and use the slot API. A typical use is a voice assistant with a long system prompt: save the state once, then restore it when the wake word fires, so the first request does not wait for prefill.

options:
  - slot_save_path:/var/lib/localai/slots

Both calls need an admin API key when authentication is on. Without slot_save_path they return 400.

The server chooses the name of every saved file. A save returns an id, and a restore takes that id. A client cannot pick a file name or a path.

# Save slot 0 of the model. The reply contains the id.
curl http://localhost:8080/v1/slots/save \
  -H "Content-Type: application/json" \
  -d '{"model": "my-model", "slot": 0}'

# Load that state back into slot 0
curl http://localhost:8080/v1/slots/restore \
  -H "Content-Type: application/json" \
  -d '{"model": "my-model", "slot": 0, "id": "0123456789abcdef0123456789abcdef"}'

The save reply gives the id, the slot, the number of tokens and bytes, and the time taken in duration_ms. The message field lists the IDs of any older saves that were deleted to make room. The restore reply has the same fields. Neither reply contains a path on the host.

Keep these points in mind:

• A client cannot choose names. The backend creates a directory for each model under slot_save_path (mode 0700) and writes a manifest.json in it. A restore works only for an id in the manifest of that model. Any other id returns 404 with no saved state with this id for this model.
• The backend keeps at most 32 saves for each model. When a save would go over that, it deletes the oldest one and lists its id in message. A save larger than 8 GiB is deleted and fails.
• A restore also checks that the file is a plain file and has the size that was recorded at save time. A file that was replaced or cut short is refused.
• Keep slot_save_path private to the user that runs LocalAI. LocalAI creates it with mode 0700 when it is missing, and writes a warning to the log when an existing directory is open to other users. The checks above cannot stop a local user who can write to the directory.
• A saved state is only as fresh as its save. To change the cached prompt, save again and use the new id.
• A saved state holds the prompt state for the model and quantisation it came from. Do not restore it into a different model, quantisation or context size. The restore call fails if the state does not fit, but a state from another model is not always detected.
• A slot that is busy with a request is served after that request ends.
• The API is for llama-cpp only. Other backends return 501.

Reference

• llama

ik_llama.cpp

ik_llama.cpp is a hard fork of llama.cpp by Iwan Kawrakow that focuses on superior CPU and hybrid GPU/CPU performance. It ships additional quantization types (IQK quants), custom quantization mixes, Multi-head Latent Attention (MLA) for DeepSeek models, and fine-grained tensor offload controls - particularly useful for running very large models on commodity CPU hardware.

Features

The ik-llama-cpp backend supports the following features:

• 📖 Text generation (GPT)
• 🧠 Embeddings
• IQK quantization types for better CPU inference performance
• Multimodal models (via clip/llava)

Setup

The backend is distributed as a separate container image and can be installed from the LocalAI backend gallery, or specified directly in a model configuration. GGUF models loaded with this backend benefit from ik_llama.cpp’s optimized CPU kernels - especially useful for MoE models and large quantized models that would otherwise be GPU-bound.

YAML configuration

To use the ik-llama-cpp backend, specify it as the backend in the YAML file:

name: my-model
backend: ik-llama-cpp
parameters:
  # Relative to the models path
  model: file.gguf

The aliases ik-llama and ik_llama are also accepted.

Reference

• ik_llama.cpp

turboquant (llama.cpp fork with TurboQuant KV-cache)

llama-cpp-turboquant is a llama.cpp fork that adds the TurboQuant KV-cache quantization scheme. It reuses the upstream llama.cpp codebase and ships as a drop-in alternative backend inside LocalAI, sharing the same gRPC server sources as the stock llama-cpp backend - so any GGUF model that runs on llama-cpp also runs on turboquant.

You would pick turboquant when you want smaller KV-cache memory pressure (longer contexts on the same VRAM) or to experiment with the fork’s quantized KV representations on top of the standard cache_type_k / cache_type_v knobs already supported by upstream llama.cpp.

Features

• Drop-in GGUF compatibility with upstream llama.cpp.
• TurboQuant KV-cache quantization (see fork README for the current set of accepted cache_type_k / cache_type_v values).
• Same feature surface as the llama-cpp backend: text generation, embeddings, tool calls, multimodal via mmproj.
• Available on CPU (AVX/AVX2/AVX512/fallback), NVIDIA CUDA 12/13, AMD ROCm/HIP, Intel SYCL f32/f16, Vulkan, and NVIDIA L4T.

Setup

turboquant ships as a separate container image in the LocalAI backend gallery. Install it like any other backend:

local-ai backends install turboquant

Or pick a specific flavor for your hardware (example tags: cpu-turboquant, cuda12-turboquant, cuda13-turboquant, rocm-turboquant, intel-sycl-f16-turboquant, vulkan-turboquant).

YAML configuration

To run a model with turboquant, set the backend in your model YAML and optionally pick quantized KV-cache types:

name: my-model
backend: turboquant
parameters:
  # Relative to the models path
  model: file.gguf
# Use TurboQuant's own KV-cache quantization schemes. The fork accepts
# the standard llama.cpp types (f16, f32, q8_0, q4_0, q4_1, q5_0, q5_1)
# and adds three TurboQuant-specific ones: turbo2, turbo3, turbo4.
# turbo3 / turbo4 auto-enable flash_attention (required for turbo K/V)
# and offer progressively more aggressive compression.
cache_type_k: turbo3
cache_type_v: turbo3
context_size: 8192

The cache_type_k / cache_type_v fields map to llama.cpp’s -ctk / -ctv flags. The stock llama-cpp backend only accepts the standard llama.cpp types - to use turbo2 / turbo3 / turbo4 you need this turboquant backend, which is where the fork’s TurboQuant code paths actually take effect. Pick q8_0 here and you’re just running stock llama.cpp KV quantization; pick turbo* and you’re running TurboQuant.

Reference

• llama-cpp-turboquant
• Tracked branch: feature/turboquant-kv-cache

vLLM

vLLM is a fast and easy-to-use library for LLM inference.

LocalAI has a built-in integration with vLLM, and it can be used to run models. You can check out vllm performance here.

Setup

Create a YAML file for the model you want to use with vllm.

To setup a model, you need to just specify the model name in the YAML config file:

name: vllm
backend: vllm
parameters:
    model: "facebook/opt-125m"

The backend will automatically download the required files in order to run the model.

Usage

Use the completions endpoint by specifying the vllm backend:

curl http://localhost:8080/v1/completions -H "Content-Type: application/json" -d '{   
   "model": "vllm",
   "prompt": "Hello, my name is",
   "temperature": 0.1, "top_p": 0.1
 }'

Passing arbitrary vLLM options with engine_args

A subset of AsyncEngineArgs is exposed as typed YAML fields (tensor_parallel_size, gpu_memory_utilization, quantization, max_model_len, dtype, trust_remote_code, enforce_eager, …). Anything else can be passed through the generic engine_args: map. Keys are forwarded verbatim to vLLM’s engine; unknown keys fail at load time with the closest valid name as a hint. Nested maps materialise into vLLM’s nested config dataclasses (SpeculativeConfig, KVTransferConfig, CompilationConfig, …).

Speculative decoding (DFlash, ngram, eagle, deepseek_mtp, …) is configured this way:

name: qwen3.5-4b-dflash
backend: vllm
parameters:
  model: Qwen/Qwen3.5-4B
context_size: 8192
max_model_len: 8192
trust_remote_code: true
quantization: fp8
template:
  use_tokenizer_template: true
engine_args:
  speculative_config:
    method: dflash
    model: z-lab/Qwen3.5-4B-DFlash
    num_speculative_tokens: 15

The shape of speculative_config follows vLLM’s SpeculativeConfig

• method picks the algorithm, the remaining keys are method-specific. Drafters from z-lab are paired with specific target models; pick the one that matches your target. The drafter loads in its native precision regardless of the target’s quantization: setting.

Another example - picking a non-default attention backend (e.g. on hardware where the default cutlass kernels aren’t supported):

engine_args:
  attention_backend: TRITON_ATTN

CLI-style engine flags in options

Engine arguments can also be written in options: with vLLM’s own CLI spelling, which is handy when copying a command line out of vLLM’s documentation:

options:
  - --quantization:gptq_marlin
  - --enable-prefix-caching
  - --kv-cache-dtype:fp8_e5m2
  - --reasoning-parser:qwen3

Rules:

• Only -- prefixed entries are treated as engine flags; everything else in options: (tool_parser:, reasoning_parser:, …) keeps its existing meaning. Both --flag:value and --flag=value are accepted.
• Dashes become underscores (--enable-prefix-caching → enable_prefix_caching) and the value is coerced to the target field’s type. A bare --flag sets a boolean field to true.
• Unknown or uncoercible flags are logged on the backend’s stderr and skipped rather than failing the load. engine_args: stays strict and is applied last, so it wins on conflict.

engine_args: remains the form to use for anything structured (nested configs, maps); options: is a convenience for flat flags.

Multi-node data parallelism

engine_args.data_parallel_size > 1 combined with the local-ai p2p-worker vllm follower lets a single model span multiple GPU nodes. See vLLM Multi-Node (Data-Parallel) for the head/follower configuration and a worked Kimi-K2.6 example.

SGLang

SGLang is a fast serving framework for LLMs and VLMs with a focus on prefix caching, speculative decoding, and multi-modal generation. LocalAI ships a gRPC backend that wraps SGLang’s async Engine, including its native function-call and reasoning parsers.

Setup

name: sglang
backend: sglang
parameters:
  model: "Qwen/Qwen3-4B"
template:
  use_tokenizer_template: true

The backend will pull the model from HuggingFace on first load.

Passing arbitrary SGLang options with engine_args

The same engine_args: map that the vLLM backend accepts is also honoured by the SGLang backend. Keys are validated against ServerArgs

• SGLang’s central configuration dataclass - and forwarded verbatim to Engine(**kwargs). Unknown keys fail at load time with the closest valid name as a hint. Unlike vLLM, ServerArgs is flat: speculative decoding fields are top-level (speculative_algorithm, speculative_draft_model_path, etc.) rather than nested under a speculative_config: dict.

The typed YAML fields shared with vLLM are mapped to their SGLang equivalents (gpu_memory_utilization → mem_fraction_static, enforce_eager → disable_cuda_graph, tensor_parallel_size → tp_size, max_model_len → context_length). Anything else, including all speculative-decoding flags, goes under engine_args:.

Speculative decoding: Gemma 4 with Multi-Token Prediction

Google publishes paired “assistant” drafters for every Gemma 4 size. The drafters use Multi-Token Prediction (MTP) to propose several candidate tokens per target step, which SGLang then verifies in parallel. Flags below are transcribed verbatim from the SGLang Gemma 4 cookbook.

For consumer GPUs in the 16-24 GB range, use E4B (8 B total / 4 B effective parameters):

name: gemma-4-e4b-mtp
backend: sglang
parameters:
  model: google/gemma-4-E4B-it
context_size: 4096
template:
  use_tokenizer_template: true
options:
  - tool_parser:gemma4
  - reasoning_parser:gemma4
engine_args:
  mem_fraction_static: 0.85
  speculative_algorithm: NEXTN
  speculative_draft_model_path: google/gemma-4-E4B-it-assistant
  speculative_num_steps: 5
  speculative_num_draft_tokens: 6
  speculative_eagle_topk: 1

For smaller cards (8-12 GB), drop to E2B (5 B total / 2 B effective) by swapping the model paths to google/gemma-4-E2B-it and google/gemma-4-E2B-it-assistant; the rest of the flags stay the same.

NEXTN is normalised to EAGLE inside ServerArgs.__post_init__, so either value works - the cookbook uses NEXTN. mem_fraction_static is the share of GPU memory SGLang reserves for the model + KV pool; 0.85 is the cookbook’s default and adapts to whatever single GPU the backend is running on.

The 31 B dense and 26 B-A4B MoE Gemma 4 variants exist in the same cookbook but require --tp-size 2, so they’re not in the gallery as single-GPU recipes.

SGLang version requirement. Gemma 4 support landed in SGLang via PR #21952. The LocalAI sglang backend pins a release that includes it; if you’ve overridden the pin to an older version, this recipe will fail with a “model architecture not recognised” error at load time.

Other speculative algorithms

speculative_algorithm: also accepts EAGLE/EAGLE3 (paired with an EAGLE-style draft head), DFLASH (block-diffusion drafters from z-lab for the Qwen3 family), STANDALONE (a smaller draft LLM verifying a larger target), and NGRAM (no draft model - pure prefix-history speculation). See SGLang’s speculative-decoding docs for the full algorithm matrix.

Tool calling and reasoning parsers

SGLang’s native parsers stream tool_calls and reasoning_content inside ChatDelta - the LocalAI Python backend wires them up per-request rather than via engine_args:. Pick a parser by name:

options:
  - tool_parser:hermes
  - reasoning_parser:deepseek_r1

The full list of registered parsers lives in sglang.srt.function_call and sglang.srt.parser.reasoning_parser.

Reasoning defaults and token budgets

Set SGLang reasoning options in the model’s options: list:

options:
  - reasoning_parser:qwen3
  - thinking_budget:512
  - reasoning_default:on
engine_args:
  enable_strict_thinking: true

thinking_budget sets a positive integer token budget for reasoning on each request. Invalid, zero, and negative values produce a warning and leave the budget unset. SGLang requires engine_args.enable_strict_thinking: true to enforce the budget. LocalAI warns if you configure a budget without that engine option. Keep the budget well below the max_tokens of your requests: if max_tokens is reached first, the budget never triggers and the whole reply can be spent on reasoning, leaving the answer empty.

effort_budgets maps the request’s reasoning_effort to its own budget, so the levels differ in how long the model may think:

options:
  - thinking_budget:256                                        # fallback: no effort, or a level not listed below
  - effort_budgets:low=256;medium=1024;high=4096;xhigh=16384;max=16384

Entries are separated by ; and use the same parsing rules as thinking_budget (invalid entries are skipped with a warning). A request whose effort is not listed falls back to thinking_budget; without either, no budget is sent. A level listed here also turns reasoning on for that request, even when reasoning_default:off is set; an explicit enable_thinking: "false" in the request metadata (also sent when the model sets reasoning.disable: true) still wins. The budget is an upper bound, not a target: the model may stop thinking earlier.

reasoning_default:on or reasoning_default:off sets the default for LocalAI’s tokenizer chat template. Request metadata enable_thinking set to "true" or "false" overrides this default. An explicit prompt bypasses tokenizer template rendering. When no default or request override is set, the template keeps its own behavior.

LocalAI signals required reasoning when the rendered prompt ends with the configured parser’s opening reasoning token. An explicit output grammar disables this detection. Configure a reasoning parser that matches your model.

The backend reads these options when it loads the model. POST /models/reload rereads model configuration files but does not update options in an already loaded backend. Restarting only the backend does not reread configuration files. Restart LocalAI after changing these options to reload both the configuration and the backend.

vllm.cpp

vllm.cpp is the LocalAI team’s C++ port of vLLM: the same continuous-batching scheduler, paged KV cache and prefix caching, with no Python at inference time. It consumes either a HuggingFace safetensors model directory or a .gguf file, and applies the model’s chat template, tool-call parsing and reasoning split engine-side.

This section is the configuration reference. For installing the backend and the ready-made models the gallery ships for it, see the vllm.cpp backend page.

Setup

name: vllm-cpp
backend: vllm-cpp
parameters:
  model: "Qwen/Qwen3-4B"
context_size: 8192
template:
  use_tokenizer_template: true

Configuring the engine with engine_args

The same engine_args: map the vLLM and SGLang backends accept is honoured here, with keys spelled exactly as vLLM’s own CLI flags - so a speculative_config or kv_transfer_config block written for vLLM works verbatim. Unknown keys are ignored rather than fatal; the engine validates the documents it is handed and reports a precise error at load.

name: qwen35-a3b
backend: vllm-cpp
parameters:
  model: "Qwen/Qwen3.5-A3B"
context_size: 16384
template:
  use_tokenizer_template: true
engine_args:
  # KV cache sizing: num_blocks * block_size tokens of cache.
  block_size: 32
  num_blocks: 1024
  # Concurrency and the per-step chunked-prefill token budget.
  max_num_seqs: 32
  max_num_batched_tokens: 8192
  # Automatic prefix caching. Omit to keep the model's own default
  # (on for dense models, off for hybrid / attention-free ones).
  enable_prefix_caching: true
  # Scheduler admission order: fcfs (default), priority, or lpm
  # (cache-aware longest-prefix-match; needs prefix caching to have any effect).
  scheduling_policy: lpm

Raising max_num_batched_tokens lets more prefill land in a single step, at the cost of decode latency for requests queued behind it. The default deliberately does not scale with max_num_seqs, which is what keeps a large concurrent prefill from blowing up the per-step activation on the hybrid architectures.

enable_prefix_caching and enable_jump_forward are tri-state at the engine boundary: omitting the key defers to a default (the model’s own capability for prefix caching, an environment variable for jump forward), while an explicit false forces the feature off. Those are genuinely different - prefix caching defaults on for dense models - so write the key only when you mean to override.

Speculative decoding

speculative_config: takes the same JSON object as vLLM’s --speculative-config. Three methods are supported.

Architecture limit. At the current engine pin, mtp and dflash are Qwen3.5 / Qwen3.6 only. The engine builds a widened speculative KV cache directly for those families rather than through the model registry, so a speculative config on any other architecture (Llama, GLM, Gemma, Mistral, …) will not work regardless of checkpoint format. ngram needs no draft weights and is not subject to this limit.

Format support. mtp and dflash now work from a .gguf target as well as safetensors. An MTP head is read from the GGUF’s nextn.* tensors when the file declares <arch>.nextn_predict_layers; a GGUF exported WITHOUT the head (converted with --no-mtp, or predating llama.cpp’s Qwen3.5 MTP support) is refused at load naming that as the reason. A DFlash draft may itself be a dflash-arch GGUF, and the target may be a GGUF too. ngram needs no draft weights and works on any format.

MTP (Multi-Token Prediction) uses a draft head shipped inside the target checkpoint’s own mtp.* tensors, so there is no second model to download. It requires a safetensors checkpoint - the mtp.* tensors do not survive GGUF conversion, and an MTP config over a .gguf model is rejected at load.

engine_args:
  speculative_config:
    method: mtp
    # Optional; defaults to the checkpoint's own head depth, which is
    # usually the right value. Must be a multiple of that depth.
    num_speculative_tokens: 1

DFlash uses a separate block-diffusion drafter that proposes a whole block of tokens in one non-autoregressive forward pass. Unlike MTP, the draft is its own checkpoint, so model: is required:

engine_args:
  speculative_config:
    method: dflash
    model: z-lab/Qwen3.6-27B-DFlash
    num_speculative_tokens: 4

The draft shares the target’s embed_tokens and lm_head, so both must come from the same model family and the target must be safetensors.

The engine does not download the draft. model: is resolved, in order, as a path as given, then as the last path segment under LocalAI’s models directory (z-lab/Qwen3.6-27B-DFlash → <models>/Qwen3.6-27B-DFlash, which is what LocalAI’s own downloader produces), then as the whole reference under the models directory. Install the draft into LocalAI first, or give an absolute path to a directory containing config.json. If none of those resolve, the load fails immediately naming every location that was tried, rather than reporting a missing checkpoint from inside the engine.

N-gram needs no draft model at all - it proposes from the prompt’s own suffix history. num_speculative_tokens is required:

engine_args:
  speculative_config:
    method: ngram
    num_speculative_tokens: 4
    prompt_lookup_min: 5
    prompt_lookup_max: 5

Auto-configuration on import. When you import a safetensors repository with backend: vllm-cpp, LocalAI reads the checkpoint’s config.json and, if it declares an MTP head (mtp_num_hidden_layers), writes speculative_config: {method: mtp} into the generated engine_args for you. An explicit speculative_config in your own config is never overwritten. Importing a DFlash draft repository is refused with a warning: a drafter cannot serve on its own, so import the target model and point speculative_config.model at the draft.

External KV cache with LMCache

kv_transfer_config: takes vLLM’s --kv-transfer-config JSON and selects an external KV-cache connector. The lm:// LMCache client lets prefill KV be stored to and reloaded from a shared lmcache.v1.server, so a prefix computed by one replica does not have to be recomputed by the next:

engine_args:
  kv_transfer_config:
    kv_connector: LMCacheConnector
    kv_role: kv_both          # required whenever kv_connector is set
    kv_connector_extra_config:
      host: 127.0.0.1
      port: 65432

kv_role is one of kv_producer (store only), kv_consumer (load only), or kv_both. An unregistered connector name, a missing role, or a malformed document fails the load with an explicit error rather than silently running without the cache.

Legacy options: list

Earlier versions configured this backend through the flat options: list, and those configs keep working. Every key in the table above is still read from there in key:value form, and engine_args wins on any key set in both:

options:
  - max_num_seqs:32
  - enable_prefix_caching:true

New configs should prefer engine_args:, which is the only place the nested speculative_config / kv_transfer_config documents can be written naturally rather than as a single-line JSON string.

Transformers

Transformers is a State-of-the-art Machine Learning library for PyTorch, TensorFlow, and JAX.

LocalAI has a built-in integration with Transformers, and it can be used to run models.

This is an extra backend - in the container images (the extra images already contains python dependencies for Transformers) is already available and there is nothing to do for the setup.

Setup

Create a YAML file for the model you want to use with transformers.

To setup a model, you need to just specify the model name in the YAML config file:

name: transformers
backend: transformers
parameters:
    model: "facebook/opt-125m"
type: AutoModelForCausalLM
quantization: bnb_4bit # One of: bnb_8bit, bnb_4bit, xpu_4bit, xpu_8bit (optional)

The backend will automatically download the required files in order to run the model.

Parameters

Type

• OVModelForCausalLM requires OpenVINO IR Text Generation models from Hugging face
• OVModelForFeatureExtraction works with any Safetensors Transformer Feature Extraction model from Huggingface (Embedding Model)

Please note that streaming is currently not implemented in AutoModelForCausalLM for Intel GPU. AMD GPU support is not implemented. Although AMD CPU is not officially supported by OpenVINO there are reports that it works: YMMV.

Embeddings

Use embeddings: true if the model is an embedding model

Inference device selection

Transformer backend tries to automatically select the best device for inference, anyway you can override the decision manually overriding with the main_gpu parameter.

Example for CUDA: main_gpu: cuda.0

Example for OpenVINO: main_gpu: AUTO:-CPU

This parameter applies to both Text Generation and Feature Extraction (i.e. Embeddings) models.

Inference Precision

Transformer backend automatically select the fastest applicable inference precision according to the device support. CUDA backend can manually enable bfloat16 if your hardware support it with the following parameter:

f16: true

Quantization

Trust Remote Code

Some models like Microsoft Phi-3 requires external code than what is provided by the transformer library. By default it is disabled for security. It can be manually enabled with: trust_remote_code: true

Maximum Context Size

Maximum context size in bytes can be specified with the parameter: context_size. Do not use values higher than what your model support.

Usage example: context_size: 8192

Auto Prompt Template

Usually chat template is defined by the model author in the tokenizer_config.json file. To enable it use the use_tokenizer_template: true parameter in the template section.

Usage example:

template:
  use_tokenizer_template: true

Custom Stop Words

Stopwords are usually defined in tokenizer_config.json file. They can be overridden with the stopwords parameter in case of need like in llama3-Instruct model.

Usage example:

stopwords:
- "<|eot_id|>"
- "<|end_of_text|>"

Usage

Use the completions endpoint by specifying the transformers model:

curl http://localhost:8080/v1/completions -H "Content-Type: application/json" -d '{   
   "model": "transformers",
   "prompt": "Hello, my name is",
   "temperature": 0.1, "top_p": 0.1
 }'

Examples

OpenVINO

A model configuration file for openvion and starling model:

name: starling-openvino
backend: transformers
parameters:
  model: fakezeta/Starling-LM-7B-beta-openvino-int8
context_size: 8192
threads: 6
f16: true
type: OVModelForCausalLM
stopwords:
- <|end_of_turn|>
- <|endoftext|>
prompt_cache_path: "cache"
prompt_cache_all: true
template:
  chat_message: |
    {{if eq .RoleName "system"}}{{.Content}}<|end_of_turn|>{{end}}{{if eq .RoleName "assistant"}}<|end_of_turn|>GPT4 Correct Assistant: {{.Content}}<|end_of_turn|>{{end}}{{if eq .RoleName "user"}}GPT4 Correct User: {{.Content}}{{end}}

  chat: |
    {{.Input}}<|end_of_turn|>GPT4 Correct Assistant:

  completion: |
    {{.Input}}

Constrained Grammars

Overview

The chat endpoint supports the grammar parameter, which allows users to specify a grammar in Backus-Naur Form (BNF). This feature enables the Large Language Model (LLM) to generate outputs adhering to a user-defined schema, such as JSON, YAML, or any other format that can be defined using BNF. For more details about BNF, see Backus-Naur Form on Wikipedia.

Setup

To use this feature, follow the installation and setup instructions on the LocalAI Functions page. Ensure that your local setup meets all the prerequisites specified for the llama.cpp backend.

💡 Usage Example

The following example demonstrates how to use the grammar parameter to constrain the model’s output to either “yes” or “no”. This can be particularly useful in scenarios where the response format needs to be strictly controlled.

Example: Binary Response Constraint

curl http://localhost:8080/v1/chat/completions -H "Content-Type: application/json" -d '{
  "model": "gpt-4",
  "messages": [{"role": "user", "content": "Do you like apples?"}],
  "grammar": "root ::= (\"yes\" | \"no\")"
}'

In this example, the grammar parameter is set to a simple choice between “yes” and “no”, ensuring that the model’s response adheres strictly to one of these options regardless of the context.

Example: JSON Output Constraint

You can also use grammars to enforce JSON output format:

curl http://localhost:8080/v1/chat/completions -H "Content-Type: application/json" -d '{
  "model": "gpt-4",
  "messages": [{"role": "user", "content": "Generate a person object with name and age"}],
  "grammar": "root ::= \"{\" \"\\\"name\\\":\" string \",\\\"age\\\":\" number \"}\"\nstring ::= \"\\\"\" [a-z]+ \"\\\"\"\nnumber ::= [0-9]+"
}'

Example: YAML Output Constraint

Similarly, you can enforce YAML format:

curl http://localhost:8080/v1/chat/completions -H "Content-Type: application/json" -d '{
  "model": "gpt-4",
  "messages": [{"role": "user", "content": "Generate a YAML list of fruits"}],
  "grammar": "root ::= \"fruits:\" newline (\"  - \" string newline)+\nstring ::= [a-z]+\nnewline ::= \"\\n\""
}'

Advanced Usage

For more complex grammars, you can define multi-line BNF rules. The grammar parser supports:

• Alternation (|)
• Repetition (*, +)
• Optional elements (?)
• Character classes ([a-z])
• String literals ("text")

Related Features

• OpenAI Functions - Function calling with structured outputs
• Text Generation - General text generation capabilities
• Moderation - OpenAI-compatible safety classification whose response is constrained to the moderation schema

Interleaved Thinking with Tool Calls

Reasoning models can “think” before they answer. When such a model also calls a tool, the useful behaviour is for the thinking and the tool call to travel together, and for that thinking to survive the tool-result round trip. LocalAI calls this interleaved thinking: a single assistant turn carries both reasoning and tool_calls, and the client hands the reasoning back on the next turn so the model’s chain of thought is not lost when the tool result is appended.

This matters because a tool-calling loop is multi-turn. The model reasons, asks for a tool, your client runs the tool, and then you call the model again with the tool result. Without interleaved thinking the reasoning produced in the first turn is discarded, and the model has to reconstruct its plan from scratch. With it, the reasoning is echoed back and the model continues where it left off.

See also: OpenAI Functions and Tools for how tool calls are extracted per backend, Text generation for the chat completions basics, and Advanced model configuration for the model options referenced below.

The round-trip contract

An assistant turn that both reasons and calls a tool returns the two fields side by side:

• reasoning holds the model’s thinking.
• tool_calls holds the structured calls.
• finish_reason is tool_calls.

Your client runs the tool, then sends the conversation back with:

1. the original assistant message (including its reasoning and tool_calls), and
2. a tool role message carrying the tool result.

LocalAI reads the returned reasoning back into the model’s context so the chain is continuous.

Field naming

OpenAI chat completions (/v1/chat/completions): the response carries reasoning alongside tool_calls. On inbound assistant messages LocalAI now also accepts reasoning_content as an alias for reasoning. This alias exists because several clients (vLLM, DeepSeek, and cogito) emit the field under the name reasoning_content; either name is accepted and mapped to the same internal field.

Anthropic Messages (/v1/messages): reasoning is carried as thinking content blocks. On the local path LocalAI emits a thinking block before the tool_use block, and reads inbound thinking blocks back into reasoning. Because local models produce no cryptographic signature, LocalAI attaches a synthetic opaque signature to the emitted block, and does not validate the signature on inbound blocks. The thinking block is only emitted when the request opts in with the thinking parameter:

{
  "model": "your-reasoning-model",
  "max_tokens": 1024,
  "thinking": { "type": "enabled" },
  "messages": [
    { "role": "user", "content": "What is the weather in Rome?" }
  ]
}

Enabling reasoning per backend

Interleaved thinking requires the backend to separate the model’s thinking from its final answer. How you turn that on depends on the backend.

llama.cpp

Set the reasoning_format model option. Accepted values: none, auto, deepseek, deepseek-legacy. auto lets the backend pick based on the model’s chat template; deepseek and deepseek-legacy force the DeepSeek-style <think>...</think> extraction.

name: my-reasoning-model
backend: llama-cpp
parameters:
  model: my-reasoning-model.gguf
options:
  - reasoning_format:auto

vLLM

Set the reasoning_parser model option to vLLM’s native reasoning parser for the model family. LocalAI also ships an auto-configuration hook (core/config/hooks_vllm.go) that sets the reasoning parser and the tool-call parser together for known families, so for gallery-imported vLLM models this is often configured for you.

name: my-vllm-model
backend: vllm
options:
  - reasoning_parser:deepseek_r1
  - tool_parser:hermes

SGLang

Set both the reasoning_parser and the tool_call_parser model options.

name: my-sglang-model
backend: sglang
options:
  - reasoning_parser:deepseek-r1
  - tool_call_parser:qwen25

Worked example

Request a chat completion with a tool defined and a prompt that requires the model to reason before acting:

curl http://localhost:8080/v1/chat/completions -H "Content-Type: application/json" -d '{
  "model": "your-reasoning-model",
  "messages": [
    { "role": "user", "content": "What is the weather in Rome?" }
  ],
  "tools": [
    {
      "type": "function",
      "function": {
        "name": "get_weather",
        "description": "Get the current weather for a city",
        "parameters": {
          "type": "object",
          "properties": {
            "city": { "type": "string" }
          },
          "required": ["city"]
        }
      }
    }
  ]
}'

The response message carries both the reasoning and the tool call, and finish_reason is tool_calls:

{
  "choices": [
    {
      "finish_reason": "tool_calls",
      "message": {
        "role": "assistant",
        "content": "",
        "reasoning": "Okay, the user is asking about the weather in Rome... I need to call get_weather with city Rome.",
        "tool_calls": [
          {
            "id": "call_abc123",
            "type": "function",
            "function": {
              "name": "get_weather",
              "arguments": "{\"city\":\"Rome\"}"
            }
          }
        ]
      }
    }
  ]
}

To continue, run get_weather, then send the conversation back with the assistant message (keeping its reasoning and tool_calls) followed by a tool message holding the result. LocalAI feeds the returned reasoning back into context so the model resumes its chain of thought.

Known limitations

Streaming Anthropic thinking blocks. In streaming mode, a thinking block is currently emitted only on the tool-call path that goes through the llama.cpp C++ autoparser. A plain streaming text-only turn, or a tool turn resolved through the inline token path, does not stream a thinking block. The equivalent non-streaming request does return one. Non-streaming emits thinking on all branches; only the streaming path has this gap.

Upstream llama.cpp leak on newest hybrid models. On the newest hybrid reasoning models (Qwen3.5 / Qwen3.6) there is an upstream llama.cpp bug where tool calls can leak into reasoning_content instead of being parsed into tool_calls. This is tracked upstream at ggml-org/llama.cpp discussion #23351.

Reasoning budget vs the tool call. If a reasoning model’s thinking exhausts the output budget (max_tokens) before it emits the tool call, no tool call is produced. Give the model enough max_tokens to cover both the reasoning and the call. In this case LocalAI reports finish_reason: "length".

Embeddings

LocalAI supports generating embeddings for text or list of tokens.

For face embeddings specifically, see the Face Recognition feature - it produces 512-d L2-normalized vectors tuned for face similarity.

For the API documentation you can refer to the OpenAI docs: https://platform.openai.com/docs/api-reference/embeddings

Model compatibility

The embedding endpoint is compatible with llama.cpp models, bert.cpp models and sentence-transformers models available in huggingface.

Choosing the model

Send the model name in the request body. If the body has no model, LocalAI uses the configured embeddings model whose name comes first alphabetically. If no embeddings model is configured, the request returns 400 Bad Request. A model name is never taken from the bearer token unless it matches a configured model name exactly.

Using Gallery Models

LocalAI provides a model gallery with pre-configured embedding models. To use a gallery model:

1. Ensure the model is available in the gallery (check Model Gallery)
2. Use the model name directly in your API calls

Example gallery models:

• qwen3-embedding-4b - Qwen3 Embedding 4B model
• qwen3-embedding-8b - Qwen3 Embedding 8B model
• qwen3-embedding-0.6b - Qwen3 Embedding 0.6B model

Example: Using Qwen3-Embedding-4B from Gallery

curl http://localhost:8080/embeddings -X POST -H "Content-Type: application/json" -d '{
  "input": "My text to embed",
  "model": "qwen3-embedding-4b",
  "dimensions": 2560
}'

Manual Setup

Create a YAML config file in the models directory. Specify the backend and the model file.

name: text-embedding-ada-002 # The model name used in the API
parameters:
  model: <model_file>
backend: "<backend>"
embeddings: true

Hugging Face embeddings

To use sentence-transformers models from Hugging Face, set backend: transformers and type: SentenceTransformer.

name: my-embeddings
backend: transformers
type: SentenceTransformer
embeddings: true
parameters:
  model: BAAI/bge-large-en-v1.5

The transformers backend loads the model with Python sentence-transformers. The gallery entry bge-large-en-v1.5 uses this setup.

Llama.cpp embeddings

Embeddings with llama.cpp are supported with the llama-cpp backend, it needs to be enabled with embeddings set to true.

name: my-awesome-model
backend: llama-cpp
embeddings: true
parameters:
  model: ggml-file.bin

Then you can use the API to generate embeddings:

curl http://localhost:8080/embeddings -X POST -H "Content-Type: application/json" -d '{
  "input": "My text",
  "model": "my-awesome-model"
}' | jq "."

Embedding chat conversations and Go-side pooling

/v1/embeddings also accepts a chat conversation via messages (a LocalAI extension), plus a per-request pooling scheme that LocalAI applies itself to the backend’s raw per-token vectors:

curl http://localhost:8080/v1/embeddings -X POST -H "Content-Type: application/json" -d '{
  "model": "my-awesome-model",
  "messages": [
    {"role": "system", "content": "You are a support agent."},
    {"role": "user", "content": "My invoice is wrong."}
  ],
  "pooling": "decayed_mean",
  "pooling_half_life_tokens": 256
}'

• One conversation per request; the response is the standard OpenAI embeddings shape with a single data[0].embedding item.
• input and messages are mutually exclusive (400 otherwise); an unknown pooling value is also a 400.
• If the model config carries both template.chat and template.chat_message, the conversation renders exactly like a chat prompt, so the embedding matches what a chat model would actually see. Otherwise a frozen role-prefixed fallback is used (<role>: <content> lines joined by newlines, empty-content messages skipped). Non-text content parts (images, audio, video) are ignored.

pooling selects how the per-token vectors are reduced to one embedding:

Go-side schemes need raw per-token vectors from the backend. Each backend declares whether an embedding result is final or per-token; LocalAI rejects a Go-side scheme for a final vector and rejects backend pass-through for a per-token matrix instead of guessing from its shape. Older backends that do not declare a layout remain compatible with backend pooling only.

llama.cpp chooses this layout when the model is loaded. LocalAI automatically adds the pooling:none backend option when a llama.cpp model sets a Go-side parameters.pooling scheme. That raw-loaded instance can switch between mean, last, and decayed_mean per request, but it cannot switch back to backend pooling without reloading. Conversely, a backend-pooled llama.cpp instance rejects per-request Go pooling. Other backends may support Go-side pooling when they explicitly return per-token vectors.

After Go-side pooling, the vector is normalized with llama.cpp’s embd_normalize rule (default L2; configurable through options: ["embd_normalize:<n>"]).

Model-level defaults live under parameters::

name: conversation-embedder
backend: llama-cpp
embeddings: true
parameters:
  model: ggml-file.bin
  pooling: decayed_mean
  pooling_half_life_tokens: 256

Go-side pooling requires an up-to-date backend that reports its embedding layout. A legacy backend fails closed for Go-side schemes with an error asking you to rebuild or update it.

💡 Examples

• Example that uses LLamaIndex and LocalAI as embedding: here.

⚠️ Common Issues and Troubleshooting

Issue: Embedding model not returning correct results

Symptoms:

• Model returns empty or incorrect embeddings
• API returns errors when calling embedding endpoint

Common Causes:

1. Incorrect model filename: Ensure you’re using the correct filename from the gallery or your model file location.

   • Gallery models use specific filenames (e.g., Qwen3-Embedding-4B-Q4_K_M.gguf)
   • Check the Model Gallery for correct filenames

2. Context size mismatch: Ensure your context_size setting doesn’t exceed the model’s maximum context length.

   • Qwen3-Embedding-4B: max 32k (32768) context
   • Qwen3-Embedding-8B: max 32k (32768) context
   • Qwen3-Embedding-0.6B: max 32k (32768) context

3. Missing embeddings: true flag: The model configuration must have embeddings: true set.

Correct Configuration Example:

name: qwen3-embedding-4b
backend: llama-cpp
embeddings: true
context_size: 32768
parameters:
  model: Qwen3-Embedding-4B-Q4_K_M.gguf

Issue: Dimension mismatch

Symptoms:

• Returned embedding dimensions don’t match expected dimensions

Solution:

• Use the dimensions parameter in your API request to specify the output dimension
• Qwen3-Embedding models support dimensions from 32 to 2560 (4B) or 4096 (8B)

curl http://localhost:8080/embeddings -X POST -H "Content-Type: application/json" -d '{
  "input": "My text",
  "model": "qwen3-embedding-4b",
  "dimensions": 1024
}'

Issue: Model not found

Symptoms:

• API returns 404 or “model not found” error

Solution:

• Ensure the model is properly configured in the models directory
• Check that the model name in your API request matches the name field in the configuration
• For gallery models, ensure the gallery is properly loaded

Qwen3 Embedding Models Specifics

The Qwen3 Embedding series models have these characteristics:

All models support:

• User-defined output dimensions (32 to max dimensions)
• Multilingual text embedding (100+ languages)
• Instruction-tuned embedding with custom instructions

Reranker

A reranking model, often referred to as a cross-encoder, is a core component in the two-stage retrieval systems used in information retrieval and natural language processing tasks. Given a query and a set of documents, it will output similarity scores.

We can use then the score to reorder the documents by relevance in our RAG system to increase its overall accuracy and filter out non-relevant results.

LocalAI supports reranker models, and you can use them by using the rerankers backend, which uses rerankers.

Usage

You can test rerankers by using container images with python (this does NOT work with core images) and a model config file like this, or by installing cross-encoder from the gallery in the UI:

name: jina-reranker-v1-base-en
backend: rerankers
parameters:
  model: cross-encoder

and test it with:

    curl http://localhost:8080/v1/rerank \
      -H "Content-Type: application/json" \
      -d '{
      "model": "jina-reranker-v1-base-en",
      "query": "Organic skincare products for sensitive skin",
      "documents": [
        "Eco-friendly kitchenware for modern homes",
        "Biodegradable cleaning supplies for eco-conscious consumers",
        "Organic cotton baby clothes for sensitive skin",
        "Natural organic skincare range for sensitive skin",
        "Tech gadgets for smart homes: 2024 edition",
        "Sustainable gardening tools and compost solutions",
        "Sensitive skin-friendly facial cleansers and toners",
        "Organic food wraps and storage solutions",
        "All-natural pet food for dogs with allergies",
        "Yoga mats made from recycled materials"
      ],
      "top_n": 3
    }'

Moderation

LocalAI exposes an OpenAI-compatible text moderation endpoint at POST /v1/moderations. It uses a local text-generation model with a constrained JSON grammar, so no separate moderation service or cloud API is required.

curl http://localhost:8080/v1/moderations \
  -H "Content-Type: application/json" \
  -d '{
    "model": "your-instruct-model",
    "input": "Text to classify"
  }'

input may be one string or an array of strings. The response contains one result per input with flagged, categories, category_scores, and category_applied_input_types fields. The category names match the OpenAI moderation API, including harassment, hate, illicit activity, self-harm, sexual content, and violence categories.

The selected model must support text completion. For consistent results, use an instruction-tuned model that follows safety-classification prompts well. LocalAI constrains the output shape, but the model determines the classification quality and confidence scores.

Time-Series Forecasting

LocalAI forecasts numeric time series with timestral.cpp, a C++/ggml port of Mistral’s Timestral models. You send one or more series, with optional covariates, to POST /v1/forecast and get quantile trajectories for the next steps.

A forecast model is not a chat model. It has its own usecase, forecast, and does not appear in the chat model picker. It shows in the gallery filter and in the /v1/models capability list.

Licence. The Timestral weights use Mistral’s Modified MIT licence. You may not use them if the global consolidated monthly revenue of your company (or your employer) exceeded USD 20 million in the preceding month, unless you get a commercial licence from Mistral AI. The restriction covers derivatives, so it also applies to the GGUF conversions in the gallery. Each gallery entry installs the licence text next to the weights. The timestral.cpp code is MIT.

Models

local-ai models install timestral-28m

The default build is F32. Install the F16 entry, for example timestral-28m-f16, for a build of about half the size. Quantized builds below F16 are not offered yet.

The engine runs on the CPU only. It is slower than the PyTorch reference at long context lengths, so keep the context short where you can and allow a long request timeout.

How much memory each build needs has not been measured yet, so the gallery sets no size.

Request

curl http://localhost:8080/v1/forecast \
  -H "Content-Type: application/json" \
  -d '{
    "model": "timestral-28m",
    "prediction_length": 4,
    "series": [
      { "id": "store-12", "target": [3.1, 3.4, null, 3.9, 4.2, 4.0, 4.4, 4.8] }
    ]
  }'

Each entry of series has these fields:

Series in one request can have different lengths and different numbers of variates or covariates. LocalAI groups them by shape, runs one forecast for each group, and returns the results in the order you sent the series.

Response

{
  "object": "forecast",
  "model": "timestral-28m",
  "prediction_length": 4,
  "quantile_levels": [0.1, 0.5, 0.9],
  "data": [
    {
      "index": 0,
      "id": "store-12",
      "variates": [
        { "index": 0, "values": [[4.4, 4.5, 4.6, 4.6], [4.7, 4.8, 4.9, 5.0], [5.0, 5.2, 5.3, 5.4]] }
      ]
    }
  ]
}

values[q][h] is the value of level quantile_levels[q] at step h. Step 0 is the first step after the last step of the history. The numbers above are an example of the shape, not real output.

Errors

The endpoint returns 400 when:

• prediction_length is less than 1, or series is empty.
• A row has the wrong number of steps, for example a known covariate that stops at the end of the history.
• A value is not a finite number, or a categorical code is not an integer. NaN and infinity are not valid JSON; use null for a missing value.
• A requested quantile is not a level of the model. The error lists the valid levels.
• The request is larger than the model limits.

Model options

Set these under options: in the model configuration:

name: timestral-28m
backend: timestral-cpp
parameters:
  model: timestral-28m-f32.gguf
threads: 4
options:
  - default_quantiles:0.1,0.5,0.9
  - max_context:0
  - max_series:256
  - max_total_points:2000000

threads sets the number of CPU threads for each forecast.

The library is not reentrant, so LocalAI runs one forecast at a time for each loaded model.

Platforms

The backend image is built for Linux on amd64 and arm64. A build for Apple silicon is wired into the build matrix, but it has not been built or tested yet.

Benchmark text models

Use local-ai benchmark to compare text inference through a running LocalAI server. Install and configure the models first. The command sends sequential, non-streaming requests to /v1/chat/completions and reports full request latency and end-to-end completion tokens per second.

Pass one or more configured model names. To compare backends, configure separate model aliases with the desired backend, then pass those aliases. Backend names alone are not model names. The command does not install, discover, or unload models; the server’s normal loading and eviction settings still apply.

For example, with models named text-llama-cpp and text-vllm configured:

local-ai benchmark text-llama-cpp text-vllm --runs 5 --warmup 1 \
  --prompt 'Explain how a rainbow forms.' --max-tokens 128

To save settings, per-model summaries, and every measured sample:

local-ai benchmark text-llama-cpp text-vllm --json > benchmark.json

For an authenticated server, set LOCALAI_API_KEY or API_KEY in the environment. The API key is excluded from the JSON report. Use --endpoint for a remote server or reverse proxy:

local-ai benchmark text-llama-cpp --endpoint https://localai.example.org/proxy/v1

The endpoint accepts a server root, an optional /v1 suffix, and trailing slashes. A reverse proxy path prefix is preserved. Redirects are refused. Credentials in the URL, query strings, and fragments are rejected.

Arguments and flags

Every request sets temperature to 0 and streaming to false. Interrupting the command cancels the active request. A failed request stops the benchmark with a model and run error; results are written only after every model succeeds.

Reading the results

Each model has minimum, mean, and maximum latency across measured requests. Latency runs from sending the request through parsing the complete response. It includes transport, queueing, prompt processing, generation, and response parsing. This command does not measure time to first token.

End-to-end completion tokens per second is the sum of server-reported completion tokens divided by the sum of full request durations. It is not decode-only speed or a substitute for llama-bench kernel measurements. If any measured response omits completion token usage, throughput is null in JSON and N/A in the table. Reported zero tokens remain zero. Missing prompt or completion counts remain null in each JSON sample; the command never estimates tokens from text length.

Warmups run separately for each model and do not appear in measurements. They can absorb model loading time, but repeated prompts can also benefit from prompt caching. With --warmup 0, measured requests can include model loading. Other clients and server queueing can affect results; compare under similar load.

Keep hardware, quantization, context size, backend settings, and prompt consistent when comparing engines. Different model tokenizers can report different token counts for the same text, and models can stop before --max-tokens. Temperature zero does not guarantee identical output across models or engines. The JSON settings describe the benchmark requests, not the server’s full model configuration; record that configuration alongside the report.

Audio to Text

Audio to text models are models that can generate text from an audio file.

The transcription endpoint allows to convert audio files to text. The endpoint supports multiple backends:

• whisper.cpp: A C++ library for audio transcription (default)
• moonshine: Ultra-fast transcription engine optimized for low-end devices
• faster-whisper: Fast Whisper implementation with CTranslate2
• WhisperX: Whisper transcription with word alignment and optional speaker diarization. Set HF_TOKEN and pass diarize=true to load WhisperX’s gated pyannote diarization pipeline.
• parakeet-cpp: A C++/ggml port of NVIDIA NeMo Parakeet (FastConformer TDT/CTC/RNNT/hybrid). Runs quantized GGUFs on CPU or GPU, emits word-level timestamps, and supports cache-aware streaming (the realtime_eou model surfaces end-of-utterance events). The same backend also loads Nemotron-3-Diarization (/v1/audio/diarization) and CED sound models (/v1/audio/classification), and can attach either as a companion to a transcription model.
• llama-cpp: Route transcription to any multimodal-audio GGUF model served by the llama-cpp backend (e.g. Qwen3-ASR, Voxtral, Qwen2-Audio). Under the hood the request is converted into a chat completion with the audio attached via the model’s audio encoder - the same path the upstream llama.cpp server uses. Set backend: llama-cpp in the model YAML and point mmproj at the matching audio encoder.
• voxtral: Voxtral-family models served by a dedicated backend
• NeMo-Speech.cpp: NVIDIA’s C++/ggml runtime for the Nemotron Speech models. Serves offline, streaming and live transcription, with VAD, punctuation, inverse text normalization and Sortformer speaker tags attached through model options, and covers diarization, speech synthesis and translation from the same backend. See the NeMo-Speech.cpp backend page for the model options.
• audio.cpp: Multi-family GGML audio engine. Serves transcription and forced alignment from families such as nemotron_asr, qwen3_asr, citrinet_asr, higgs_audio_stt and voxtral_realtime, and covers diarization, VAD, TTS and source separation from the same backend. See the audio.cpp backend page for the model options.

The endpoint input supports all the audio formats supported by ffmpeg.

Looking for “who spoke when” instead of a flat transcript? See Speaker Diarization - /v1/audio/diarization returns time-stamped speaker segments and supports the rttm format used by pyannote.metrics.

Usage

Once LocalAI is started and whisper models are installed, you can use the /v1/audio/transcriptions API endpoint.

For instance, with cURL:

curl http://localhost:8080/v1/audio/transcriptions -H "Content-Type: multipart/form-data" -F file="@<FILE_PATH>" -F model="<MODEL_NAME>"

When usage statistics are enabled, successful requests to /v1/audio/transcriptions and /audio/transcriptions contribute request counts and elapsed time for the requested model name, including an alias. This includes streaming responses. Token counts remain zero because transcription results do not provide canonical token usage. Failed transcriptions, including errors reported within a stream, do not count as successful usage.

When API tracing is enabled, multipart transcription requests appear in Traces with the model name, response, status, and elapsed time. The captured request body contains metadata marked multipart upload omitted; API traces do not store the uploaded audio. Response capture follows the configured trace size limit. Backend traces have their own payload capture behavior.

Example

Download one of the models from here in the models folder, and create a YAML file for your model:

name: whisper-1
backend: whisper
parameters:
  model: whisper-en

The transcriptions endpoint then can be tested like so:

## Get an example audio file
wget --quiet --show-progress -O gb1.ogg https://upload.wikimedia.org/wikipedia/commons/1/1f/George_W_Bush_Columbia_FINAL.ogg

## Send the example audio file to the transcriptions endpoint
curl http://localhost:8080/v1/audio/transcriptions -H "Content-Type: multipart/form-data" -F file="@$PWD/gb1.ogg" -F model="whisper-1"

Result:

{
  "segments":[{"id":0,"start":0,"end":9640000000,"text":" My fellow Americans, this day has brought terrible news and great sadness to our country.","tokens":[50364,1222,7177,6280,11,341,786,575,3038,6237,2583,293,869,22462,281,527,1941,13,50846]},{"id":1,"start":9640000000,"end":15960000000,"text":" At 9 o'clock this morning, Mission Control and Houston lost contact with our Space Shuttle","tokens":[1711,1722,277,6,9023,341,2446,11,20170,12912,293,18717,2731,3385,365,527,8705,13870,10972,51162]},{"id":2,"start":15960000000,"end":16960000000,"text":" Columbia.","tokens":[17339,13,51212]},{"id":3,"start":16960000000,"end":24640000000,"text":" A short time later, debris was seen falling from the skies above Texas.","tokens":[316,2099,565,1780,11,21942,390,1612,7440,490,264,25861,3673,7885,13,51596]},{"id":4,"start":24640000000,"end":27200000000,"text":" The Columbia's lost.","tokens":[440,17339,311,2731,13,51724]},{"id":5,"start":27200000000,"end":29920000000,"text":" There are no survivors.","tokens":[821,366,572,18369,13,51860]},{"id":6,"start":29920000000,"end":32920000000,"text":" And board was a crew of seven.","tokens":[50364,400,3150,390,257,7260,295,3407,13,50514]},{"id":7,"start":32920000000,"end":39780000000,"text":" Colonel Rick Husband, Lieutenant Colonel Michael Anderson, Commander Laurel Clark, Captain","tokens":[28478,11224,21282,4235,11,28412,28478,5116,18768,11,20857,27270,75,18572,11,10873,50857]},{"id":8,"start":39780000000,"end":50020000000,"text":" David Brown, Commander William McCool, Dr. Cooltna Chavla, and Elon Ramon, a Colonel","tokens":[4389,8030,11,20857,6740,4050,34,1092,11,2491,13,8561,83,629,761,706,875,11,293,28498,9078,266,11,257,28478,51369]},{"id":9,"start":50020000000,"end":52800000000,"text":" in the Israeli Air Force.","tokens":[294,264,19974,5774,10580,13,51508]},{"id":10,"start":52800000000,"end":58480000000,"text":" These men and women assumed great risk in the service to all humanity.","tokens":[1981,1706,293,2266,15895,869,3148,294,264,2643,281,439,10243,13,51792]},{"id":11,"start":58480000000,"end":63120000000,"text":" And an age when Space Flight has come to seem almost routine.","tokens":[50364,400,364,3205,562,8705,28954,575,808,281,1643,1920,9927,13,50596]},{"id":12,"start":63120000000,"end":68800000000,"text":" It is easy to overlook the dangers of travel by rocket and the difficulties of navigating","tokens":[467,307,1858,281,37826,264,27701,295,3147,538,13012,293,264,14399,295,32054,50880]},{"id":13,"start":68800000000,"end":72640000000,"text":" the fierce outer atmosphere of the Earth.","tokens":[264,25341,10847,8018,295,264,4755,13,51072]},{"id":14,"start":72640000000,"end":78040000000,"text":" These astronauts knew the dangers and they faced them willingly.","tokens":[1981,28273,2586,264,27701,293,436,11446,552,44675,13,51342]},{"id":15,"start":78040000000,"end":83040000000,"text":" Knowing they had a high and noble purpose in life.","tokens":[25499,436,632,257,1090,293,20171,4334,294,993,13,51592]},{"id":16,"start":83040000000,"end":90800000000,"text":" Because of their courage and daring and idealism, we will miss them all the more.","tokens":[50364,1436,295,641,9892,293,43128,293,7157,1434,11,321,486,1713,552,439,264,544,13,50752]},{"id":17,"start":90800000000,"end":96560000000,"text":" All Americans today are thinking as well of the families of these men and women who have","tokens":[1057,6280,965,366,1953,382,731,295,264,4466,295,613,1706,293,2266,567,362,51040]},{"id":18,"start":96560000000,"end":100440000000,"text":" been given this sudden shock in grief.","tokens":[668,2212,341,3990,5588,294,18998,13,51234]},{"id":19,"start":100440000000,"end":102400000000,"text":" You're not alone.","tokens":[509,434,406,3312,13,51332]},{"id":20,"start":102400000000,"end":105440000000,"text":" Our entire nation agrees with you.","tokens":[2621,2302,4790,26383,365,291,13,51484]},{"id":21,"start":105440000000,"end":112360000000,"text":" And those you loved will always have the respect and gratitude of this country.","tokens":[400,729,291,4333,486,1009,362,264,3104,293,16935,295,341,1941,13,51830]},{"id":22,"start":112360000000,"end":116600000000,"text":" The cause in which they died will continue.","tokens":[50364,440,3082,294,597,436,4539,486,2354,13,50576]},{"id":23,"start":116600000000,"end":124240000000,"text":" Man kind is led into the darkness beyond our world by the inspiration of discovery and the","tokens":[2458,733,307,4684,666,264,11262,4399,527,1002,538,264,10249,295,12114,293,264,50958]},{"id":24,"start":124240000000,"end":127000000000,"text":" longing to understand.","tokens":[35050,281,1223,13,51096]},{"id":25,"start":127000000000,"end":131160000000,"text":" Our journey into space will go on.","tokens":[2621,4671,666,1901,486,352,322,13,51304]},{"id":26,"start":131160000000,"end":136480000000,"text":" In the skies today, we saw destruction and tragedy.","tokens":[682,264,25861,965,11,321,1866,13563,293,18563,13,51570]},{"id":27,"start":136480000000,"end":142080000000,"text":" As farther than we can see, there is comfort and hope.","tokens":[1018,20344,813,321,393,536,11,456,307,3400,293,1454,13,51850]},{"id":28,"start":142080000000,"end":149800000000,"text":" In the words of the prophet Isaiah, lift your eyes and look to the heavens who created","tokens":[50364,682,264,2283,295,264,18566,27263,11,5533,428,2575,293,574,281,264,26011,567,2942,50750]},{"id":29,"start":149800000000,"end":151640000000,"text":" all these.","tokens":[439,613,13,50842]},{"id":30,"start":151640000000,"end":159960000000,"text":" He who brings out the story hosts one by one and calls them each by name because of his great","tokens":[634,567,5607,484,264,1657,21573,472,538,472,293,5498,552,1184,538,1315,570,295,702,869,51258]},{"id":31,"start":159960000000,"end":163400000000,"text":" power and mighty strength.","tokens":[1347,293,21556,3800,13,51430]},{"id":32,"start":163400000000,"end":166400000000,"text":" Not one of them is missing.","tokens":[1726,472,295,552,307,5361,13,51580]},{"id":33,"start":166400000000,"end":173600000000,"text":" The same creator who names the stars also knows the names of the seven souls we mourn","tokens":[50364,440,912,14181,567,5288,264,6105,611,3255,264,5288,295,264,3407,16588,321,22235,77,50724]},{"id":34,"start":173600000000,"end":175600000000,"text":" today.","tokens":[965,13,50824]},{"id":35,"start":175600000000,"end":183160000000,"text":" The crew of the shuttle Columbia did not return safely to earth yet we can pray that all","tokens":[440,7260,295,264,26728,17339,630,406,2736,11750,281,4120,1939,321,393,3690,300,439,51202]},{"id":36,"start":183160000000,"end":185840000000,"text":" are safely home.","tokens":[366,11750,1280,13,51336]},{"id":37,"start":185840000000,"end":192600000000,"text":" May God bless the grieving families and may God continue to bless America.","tokens":[1891,1265,5227,264,48454,4466,293,815,1265,2354,281,5227,3374,13,51674]},{"id":38,"start":196400000000,"end":206400000000,"text":" [BLANK_AUDIO]","tokens":[50364,542,37592,62,29937,60,50864]}],
  "text":"My fellow Americans, this day has brought terrible news and great sadness to our country. At 9 o'clock this morning, Mission Control and Houston lost contact with our Space Shuttle Columbia. A short time later, debris was seen falling from the skies above Texas. The Columbia's lost. There are no survivors. And board was a crew of seven. Colonel Rick Husband, Lieutenant Colonel Michael Anderson, Commander Laurel Clark, Captain David Brown, Commander William McCool, Dr. Cooltna Chavla, and Elon Ramon, a Colonel in the Israeli Air Force. These men and women assumed great risk in the service to all humanity. And an age when Space Flight has come to seem almost routine. It is easy to overlook the dangers of travel by rocket and the difficulties of navigating the fierce outer atmosphere of the Earth. These astronauts knew the dangers and they faced them willingly. Knowing they had a high and noble purpose in life. Because of their courage and daring and idealism, we will miss them all the more. All Americans today are thinking as well of the families of these men and women who have been given this sudden shock in grief. You're not alone. Our entire nation agrees with you. And those you loved will always have the respect and gratitude of this country. The cause in which they died will continue. Man kind is led into the darkness beyond our world by the inspiration of discovery and the longing to understand. Our journey into space will go on. In the skies today, we saw destruction and tragedy. As farther than we can see, there is comfort and hope. In the words of the prophet Isaiah, lift your eyes and look to the heavens who created all these. He who brings out the story hosts one by one and calls them each by name because of his great power and mighty strength. Not one of them is missing. The same creator who names the stars also knows the names of the seven souls we mourn today. The crew of the shuttle Columbia did not return safely to earth yet we can pray that all are safely home. May God bless the grieving families and may God continue to bless America. [BLANK_AUDIO]"
}

You can also specify the response_format parameter to be one of lrc, srt, vtt, text, json or verbose_json (default):

## Send the example audio file to the transcriptions endpoint
curl http://localhost:8080/v1/audio/transcriptions -H "Content-Type: multipart/form-data" -F file="@$PWD/gb1.ogg" -F model="whisper-1" -F response_format="srt"

Result (first few lines):

1
00:00:00,000 --> 00:00:09,640
My fellow Americans, this day has brought terrible news and great sadness to our country.

2
00:00:09,640 --> 00:00:15,960
At 9 o'clock this morning, Mission Control and Houston lost contact with our Space Shuttle

3
00:00:15,960 --> 00:00:16,960
Columbia.

4
00:00:16,960 --> 00:00:24,640
A short time later, debris was seen falling from the skies above Texas.

5
00:00:24,640 --> 00:00:27,200
The Columbia's lost.

6
00:00:27,200 --> 00:00:29,920
There are no survivors.

Supported request parameters

In addition to file and model, the endpoint accepts the following multipart form fields, matching the OpenAI audio transcription API:

If speaker diarization fails after transcription succeeded, the WhisperX backend logs the error and returns the transcript without speaker labels. Other transcription failures return an error instead of an empty transcript. Diarization still requires HF_TOKEN.

The response body for verbose_json includes text, language, duration, and segments[] (with speaker populated when diarization is enabled).

Streaming transcriptions

Set -F stream=true to receive token-by-token SSE events as the backend produces them. The event shape matches the OpenAI streaming transcription format:

curl -N http://localhost:8080/v1/audio/transcriptions \
  -H "Content-Type: multipart/form-data" \
  -F file="@sample.wav" \
  -F model="whisper-1" \
  -F stream=true

data: {"type":"transcript.text.delta","delta":"And so, my"}

data: {"type":"transcript.text.delta","delta":" fellow Americans..."}

data: {"type":"transcript.text.done","text":"And so, my fellow Americans..."}

data: [DONE]

Backends that do not natively stream tokens fall back to emitting one delta plus a done event with the full text - the SSE contract is identical either way.

Using the llama-cpp backend with an audio-capable model

Any GGUF model whose mmproj contains an audio encoder can be used for transcription via the llama-cpp backend. This reuses the model’s own audio front-end rather than shelling out to whisper.cpp, which is useful when you want a single backend serving both chat-with-audio and transcription.

Example using ggml-org/Qwen3-ASR-0.6B-GGUF:

name: qwen3-asr
backend: llama-cpp
parameters:
  model: Qwen3-ASR-0.6B-Q8_0.gguf
mmproj: mmproj-Qwen3-ASR-0.6B-Q8_0.gguf