Models/GPT-5.1

GPT-5.1

gpt-5.1

Powerful model with excellent performance and efficiency.

High PerformanceBalancedBest Value

Input¥1.80

Output¥15.00

per 1M tokens

High Performance

Excellent capability

Balanced

Performance meets efficiency

Best Value

Great price-performance

Reliable

Consistent outputs

API Documentation

View complete API reference with all parameters and examples.

View Docs

Advanced Features

Streaming

Enable real-time streaming responses with Server-Sent Events.

{
  "model": "gpt-5.1",
  "stream": true,
  "messages": [...]
}

Function Calling (Tools)

Enable the model to use tools and call functions.

{
  "model": "gpt-5.1",
  "tools": [{
    "type": "function",
    "function": {
      "name": "get_weather",
      "description": "Get current weather for a location",
      "parameters": {
        "type": "object",
        "properties": {
          "location": {"type": "string", "description": "City name"}
        },
        "required": ["location"]
      }
    }
  }],
  "messages": [{"role": "user", "content": "What's the weather in Tokyo?"}]
}

JSON Mode

Get structured JSON responses from the model.

{
  "model": "gpt-5.1",
  "response_format": {"type": "json_object"},
  "messages": [{"role": "user", "content": "Extract info as JSON: John is 30 years old"}]
}

API Parameters Reference

Parameter	Type	Required	Description
model	string	Yes	Model identifier (e.g., gpt-5.1)
messages	array	Yes	Array of message objects with role and content
max_tokens	integer	No	Maximum tokens in the response
stream	boolean	No	Enable streaming responses (SSE)
temperature	number	No	Sampling temperature (0.0 - 2.0)
top_p	number	No	Nucleus sampling threshold (0.0 - 1.0)
tools	array	No	Function calling tools definition
response_format	object	No	Output format (e.g., json_object)

Full API Documentation

View complete API reference with streaming, thinking, and more.

View Documentation

Pricing

Input

¥1.80

per 1M tokens

Output

¥15.00

per 1M tokens

Billing: Cost = (input_tokens * input_price + output_tokens * output_price) / 1,000,000