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Beta APIThis API is in beta stage and may have breaking changes. Use with caution in production environments.
Stateless OnlyThis API is stateless - each request is independent and no conversation state is persisted between requests. You must include the full conversation history in each request.
OpenRouter’s Responses API Beta provides OpenAI-compatible access to multiple AI models through a unified interface, designed to be a drop-in replacement for OpenAI’s Responses API. This stateless API offers enhanced capabilities including reasoning, tool calling, and web search integration, with each request being independent and no server-side state persisted.

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Base URL

https://openrouter.ai/api/v1/responses

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Authentication

All requests require authentication using your OpenRouter API key: 
const response = await fetch('https://openrouter.ai/api/v1/responses', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer YOUR_OPENROUTER_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'openai/o4-mini',
    input: 'Hello, world!',
  }),
});

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Core Features

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Basic Usage

Learn the fundamentals of making requests with simple text input and handling responses.

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Reasoning

Access advanced reasoning capabilities with configurable effort levels and encrypted reasoning chains.

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Tool Calling

Integrate function calling with support for parallel execution and complex tool interactions. Enable web search capabilities with real-time information retrieval and citation annotations.

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Error Handling

The API returns structured error responses: 
{
  "error": {
    "code": "invalid_prompt",
    "message": "Missing required parameter: 'model'."
  },
  "metadata": null
}
For comprehensive error handling guidance, see Error Handling.

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Rate Limits

Standard OpenRouter rate limits apply. See API Limits for details.