POST
/
v1
/
chat
/
completions
Chat
curl --request POST \
  --url https://api.matterai.so/v1/chat/completions \
  --header 'Content-Type: application/json' \
  --data '{
  "model": "<string>",
  "messages": [
    {
      "role": "<string>",
      "content": "<string>"
    }
  ],
  "stream": true,
  "max_tokens": 123,
  "reasoning": {
    "effort": "<string>"
  },
  "response_format": {
    "type": "<string>"
  },
  "temperature": 123,
  "top_p": 123
}'
{
  "400": {},
  "401": {},
  "429": {},
  "500": {},
  "id": "<string>",
  "object": "<string>",
  "created": 123,
  "model": "<string>",
  "choices": [
    {
      "index": 123,
      "message": {
        "role": "<string>",
        "content": "<string>"
      },
      "finish_reason": "<string>"
    }
  ],
  "usage": {
    "prompt_tokens": 123,
    "completion_tokens": 123,
    "total_tokens": 123
  }
}

​
Authentication

All API requests require authentication using a Bearer token. You can obtain your API key from the Matter AI Console. 
Authorization: Bearer MATTER_API_KEY
Keep your API key secure and never expose it in client-side code. Get your API key from the Matter AI console.

​
Request

​
model
string
required
The model to use for completion. Currently supports "axon".
​
messages
array
required
An array of message objects that make up the conversation.
​
stream
boolean
default:"false"
Whether to stream the response as it’s generated.
​
max_tokens
integer
default:"2000"
The maximum number of tokens to generate in the completion.
​
reasoning
object
Configuration for reasoning capabilities.
​
response_format
object
The format of the response.
​
temperature
number
default:"0.1"
Controls randomness in the output. Higher values make output more random, lower values make it more focused and deterministic. Range: 0.0 to 2.0.
​
top_p
number
default:"1"
Controls diversity via nucleus sampling. Range: 0.0 to 1.0.

​
Response

​
id
string
A unique identifier for the chat completion.
​
object
string
The object type, which is always "chat.completion".
​
created
integer
The Unix timestamp (in seconds) of when the chat completion was created.
​
model
string
The model used for the chat completion.
​
choices
array
A list of chat completion choices.
​
usage
object
Usage statistics for the completion request.

​
Example Request

curl --location 'https://api.matterai.so/v1/chat/completions' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer MATTER_API_KEY' \
--data '{
    "model": "axon-code",
    "messages": [
        {
            "role": "system",
            "content": "You are a helpful assistant"
        },
        {
            "role": "user",
            "content": "Hi"
        }
    ],
    "stream": true,
    "max_tokens": 2000,
    "reasoning": {
        "effort": "none"
    },
    "response_format": {
        "type": "text"
    },
    "temperature": 0.1,
    "top_p": 1
}'

​
Example Response

{
    "id": "chatcmpl-cd3ac60c-9746-457b-b4fa-aca53a993249",
    "choices": [
        {
            "index": 0,
            "message": {
                "role": "assistant",
                "content": "Axon is an Agentic LLM Model for coding by MatterAI, designed as an elite software engineering assistant for architecting mission-critical systems."
            },
            "finish_reason": "stop"
        }
    ],
    "created": 1756372473,
    "model": "axon-code",
    "object": "chat.completion",
    "usage": {
        "prompt_tokens": 34,
        "completion_tokens": 1031,
        "total_tokens": 1065,
        "completion_tokens_details": {
            "reasoning_tokens": 1001
        },
        "prompt_tokens_details": {
            "cached_tokens": 0
        }
    }
}

​
Streaming

When stream is set to true, the API will return a stream of Server-Sent Events (SSE). Each event contains a JSON object with the partial response: 
data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1677652288,"model":"axon","choices":[{"index":0,"delta":{"content":"Hello"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1677652288,"model":"axon","choices":[{"index":0,"delta":{"content":"!"},"finish_reason":null}]}

data: {"id":"chatcmpl-abc123","object":"chat.completion.chunk","created":1677652288,"model":"axon","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}

data: [DONE]

​
Error Responses

The API returns standard HTTP status codes to indicate success or failure:
​
400
Bad Request
Invalid request parameters or malformed JSON.
​
401
Unauthorized
Invalid or missing API key.
​
429
Rate Limited
Too many requests. Please slow down.
​
500
Internal Server Error
Server error. Please try again later.
Example error response: 
{
  "error": {
    "message": "Invalid API key provided",
    "type": "invalid_request_error",
    "code": "invalid_api_key"
  }
}