Chat Completions

POST /v1/chat/completions

OpenAI-compatible chat completions with streaming support.

Request

{
  "model": "auto",
  "messages": [
    {"role": "system", "content": "You are helpful."},
    {"role": "user", "content": "Hello"}
  ],
  "temperature": 0.7,
  "max_tokens": 2048,
  "stream": false
}

mycellm routing (optional)

{
  "model": "auto",
  "messages": [{"role": "user", "content": "Write code"}],
  "mycellm": {
    "min_tier": "capable",
    "required_tags": ["code"],
    "routing": "quality",
    "fallback": "downgrade"
  }
}

Field	Type	Description
min_tier	string	tiny, fast, capable, frontier
required_tags	string[]	code, reasoning, vision
routing	string	best (quality) or fastest (latency)
fallback	string	downgrade or reject

Response

{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1711234567,
  "model": "Qwen2.5-3B-Instruct-Q8_0",
  "choices": [{
    "index": 0,
    "message": {"role": "assistant", "content": "Hello!"},
    "finish_reason": "stop"
  }],
  "usage": {
    "prompt_tokens": 12,
    "completion_tokens": 3,
    "total_tokens": 15
  }
}

Streaming

Set "stream": true. Response is Server-Sent Events:

data: {"id":"chatcmpl-abc","object":"chat.completion.chunk","model":"Qwen2.5-3B","choices":[{"delta":{"content":"Hello"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc","object":"chat.completion.chunk","model":"Qwen2.5-3B","choices":[{"delta":{},"finish_reason":"stop"}]}

data: [DONE]