Chat Completions

The LLMTR gateway is compatible with the OpenAI Chat Completions API. All requests POST to https://llmtr.com/v1/chat/completions.

Request

POST /v1/chat/completions
Authorization: Bearer sk_your_key
Content-Type: application/json

Body parameters

Field	Type	Required	Description
`model`	string	yes	Canonical model ID (e.g. `openai/gpt-4o`)
`messages`	array	yes	OpenAI `messages` format
`stream`	boolean	no	`true` enables SSE stream
`temperature`	number	no	0-2 range, model-specific default
`max_tokens`	integer	no	Output token cap
`top_p`	number	no	Nucleus sampling
`frequency_penalty`	number	no	-2 to 2
`presence_penalty`	number	no	-2 to 2
`stop`	string/array	no	Stop sequences
`response_format`	object	no	`{ "type": "json_object" }` on supported models
`tools`	array	no	Function calling (supported models)
`tool_choice`	string/object	no	`auto`, `none` or specific tool

Basic example

curl https://llmtr.com/v1/chat/completions \
  -H "Authorization: Bearer sk_your_key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-4o",
    "messages": [
      {"role": "system", "content": "You are a concise assistant."},
      {"role": "user", "content": "What is LLMTR?"}
    ],
    "temperature": 0.3,
    "max_tokens": 200
  }'

Response

Successful response mirrors OpenAI’s format exactly:

{
  "id": "chatcmpl-xxx",
  "object": "chat.completion",
  "created": 1739200000,
  "model": "openai/gpt-4o",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "LLMTR is a unified gateway..."
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 24,
    "completion_tokens": 52,
    "total_tokens": 76
  }
}

Model identifier format

Models are always referenced as provider/model:

openai/gpt-4o
anthropic/claude-sonnet-4.5
google/gemini-2.5-flash
deepseek/deepseek-v4-flash
mistral/mistral-large-latest

Use the dashboard model list or /api/models for the full catalog.

Provider-specific behaviors

Some providers support extra body fields or custom options. You can include supported fields directly in the request body.

Xiaomi MiMo

Applies to mimo/mimo-v2-pro, mimo/mimo-v2-omni, mimo/mimo-v2-flash.

Enabling web search. Both forms are accepted:

// Option 1: Via the tools field
{ "tools": [{ "type": "web_search" }] }

// Option 2: Via the body field
{ "webSearchEnabled": true }

Search-enabled requests may carry extra provider-side charges. Check the current model pricing before sending production traffic.

Thinking control. On supported models, add thinking to the body to control this behavior:

{ "thinking": { "type": "enabled" } }   // or "disabled"

Error codes

HTTP	`error.type`	Meaning
400	`invalid_request_error`	Invalid parameter / missing field
401	`auth_error`	Invalid or expired API key
403	`forbidden`	No access to the model
429	`rate_limit_exceeded`	Rate limit hit
500	`internal_error`	Gateway internal error
502	`provider_error`	Upstream provider failure

See Errors for the full list.