POST
/
v1
/
chat
/
completions
curl -X POST https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "messages": [
      {"role": "system", "content": "You are a helpful assistant."},
      {"role": "user", "content": "Hello!"}
    ],
    "stream": true,
    "max_tokens": 16000,
    "thinking": {
      "type": "enabled",
      "budget_tokens": 10240
    }
  }'

{
  "id": "chatcmpl-claude-think-123",
  "object": "chat.completion",
  "created": 1677652288,
  "model": "claude-sonnet-4-20250514",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello! How can I help you today?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 25,
    "completion_tokens": 500,
    "total_tokens": 525
  }
}
Official documentation: https://docs.anthropic.com/en/docs/build-with-claude/extended-thinking
Enable extended thinking mode for Claude models using the OpenAI-compatible chat completions format.

​
Authentication

Authorization: Bearer YOUR_API_KEY

​
Request Parameters

​
model
string
required
The Claude model ID. For example: claude-sonnet-4-20250514.
​
messages
array
required
A list of messages comprising the conversation.
​
thinking
object
required
Thinking configuration object.
  • type (string): Set to "enabled" to activate thinking
  • budget_tokens (integer): Maximum tokens for the thinking process
​
max_tokens
integer
Maximum number of tokens to generate.
​
stream
boolean
default:"false"
Whether to stream responses.
​
temperature
number
default:"1"
Sampling temperature between 0 and 2.
curl -X POST https://www.anyfast.ai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "messages": [
      {"role": "system", "content": "You are a helpful assistant."},
      {"role": "user", "content": "Hello!"}
    ],
    "stream": true,
    "max_tokens": 16000,
    "thinking": {
      "type": "enabled",
      "budget_tokens": 10240
    }
  }'

{
  "id": "chatcmpl-claude-think-123",
  "object": "chat.completion",
  "created": 1677652288,
  "model": "claude-sonnet-4-20250514",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello! How can I help you today?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 25,
    "completion_tokens": 500,
    "total_tokens": 525
  }
}