Chat Completions

OpenAI-compatible chat completions endpoint.

POST/v1/chat/completions

Request Parameters

Parameter	Type	Required	Description
`model`	string	Yes	The model to use for completion (e.g. "gpt-4o", "claude-sonnet-4-20250514")
`messages`	array	Yes	Array of message objects with role (system/user/assistant) and content
`max_tokens`	integer	No	Maximum number of tokens to generate. Defaults to model max.
`temperature`	number	No	Sampling temperature between 0 and 2. Higher = more creative. Default: 1
`top_p`	number	No	Nucleus sampling. Considers tokens with top_p probability mass. Default: 1
`stream`	boolean	No	If true, returns a stream of server-sent events. Default: false

Response Format

Non-streaming responses return a complete JSON object:

Response

{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1712678400,
  "model": "gpt-4o",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello! How can I help you today?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 12,
    "completion_tokens": 9,
    "total_tokens": 21
  }
}

Streaming

When stream: true, the response is delivered as Server-Sent Events (SSE). Each event contains a chunk of the completion:

SSE stream format

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1712678400,"model":"gpt-4o","choices":[{"index":0,"delta":{"role":"assistant"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1712678400,"model":"gpt-4o","choices":[{"index":0,"delta":{"content":"Hello"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1712678400,"model":"gpt-4o","choices":[{"index":0,"delta":{"content":"!"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1712678400,"model":"gpt-4o","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}

data: [DONE]

The stream ends with a data: [DONE] event.

Streaming Example

curl https://api.osiris.ai/v1/chat/completions \
  -H "Authorization: Bearer sk-osiris-YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o",
    "stream": true,
    "messages": [{"role": "user", "content": "Hello!"}]
  }'