Chat Completions

Chat Completions is the most commonly used conversation API. It is suitable for chat, coding assistants, summarization, classification, tool calling, and multi-turn conversations.

Endpoint

POST /v1/chat/completions

Full URL:

https://www.routeapi.ai/v1/chat/completions

Request example

curl https://www.routeapi.ai/v1/chat/completions \
  -H "Authorization: Bearer $ROUTEAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o",
    "messages": [
      { "role": "user", "content": "Introduce RouteAPI in one sentence" }
    ]
  }'

Request parameters

Field	Type	Required	Description
model	string	Yes	Model ID, must be available to the current account
messages	array	Yes	Conversation message list
stream	boolean	No	Whether to use SSE streaming output
temperature	number	No	Sampling temperature
top_p	number	No	nucleus sampling parameter
max_tokens	number	No	Maximum output token count
tools	array	No	Tool definitions
tool_choice	string/object	No	Tool choice strategy
response_format	object	No	JSON mode or JSON Schema
stream_options	object	No	Extra streaming output options

messages format

[
  { "role": "system", "content": "You are a rigorous technical assistant." },
  { "role": "user", "content": "Explain what an API gateway is." }
]

Common roles:

Role	Description
system	System prompt
user	User input
assistant	Historical model response
tool	Tool call result

Response example

{
  "id": "chatcmpl_xxx",
  "object": "chat.completion",
  "created": 1730000000,
  "model": "gpt-4o",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "RouteAPI is an API gateway for unified access to multiple AI model services."
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 24,
    "completion_tokens": 18,
    "total_tokens": 42
  }
}

Compatibility notes

• The same parameter may be supported differently by different model services.
• If the request includes optional parameters such as tools, response_format, or stream_options, confirm that the selected model supports the corresponding capability first.
• Optional parameters explicitly passed as 0 or false should be treated as user-provided values.