OpenAI Responses API

OpenAI-compatible Responses API

The OpenAI Responses API is a modern, unified API designed to simplify how developers interact with OpenAI’s language models. It provides a consistent interface for generating text, structured data, or multi-modal outputs—such as text, images, and JSON—within a single, flexible endpoint called the Responses endpoint.

This API replaces many older, purpose-specific endpoints and offers a streamlined way to access advanced model capabilities while maintaining clarity, extensibility, and performance.

What Is the OpenAI Responses API?

Traditionally, OpenAI offered several separate endpoints such as /completions, /chat/completions, and /edits, each with its own input and output structures. The Responses API unifies these into a single, coherent protocol. Through this unified API, developers can:

• Generate natural language responses from models.

• Incorporate structured or function-like outputs directly.

• Stream model outputs in real time.

• Include context, tools, and media types within one request structure.

This design greatly simplifies integration across a variety of tasks, from chatbots and document summarization to automated reasoning or data annotation.

Advantages Over Traditional APIs

The OpenAI Responses API offers several key benefits compared to older protocols or vendor-specific interfaces:

1. Unified Design All generation tasks—chat, completion, multi-turn conversation, structured outputs—share one consistent interface. This eliminates the need to handle multiple data schemas.

2. Typed and Flexible Outputs The API supports text, JSON, and other structured outputs, allowing developers to receive directly usable data without custom post‑processing.

3. Tool and Function Calling Integration Function calling and tool invocation are natively supported via the same endpoint, simplifying orchestration between models and external services.

4. Extensible Streaming The streaming mechanism allows token‑level or chunk‑level updates in real time, improving user experience for chat and live assistant scenarios.

5. Future‑Proof Compatibility The unified protocol makes it easier for OpenAI (and other providers) to introduce new capabilities without forcing major client‑side changes.

Infron AI’s Support for the OpenAI Responses API

Infron AI is an AI integration and orchestration layer that provides unified access to multiple AI model providers. To ensure maximum compatibility and developer convenience, Infron AI includes native support for the OpenAI Responses API.

Key Features in Infron AI’s Implementation:

1. Protocol Compatibility Infron AI can route and translate Requests and Responses that conform to the OpenAI Responses API specification. Developers can use the same API format, regardless of which backend provider or model family they call.

2. Multi-Provider Routing With support for multiple model backends, Infron AI acts as a compatibility gateway. The same Responses API call can be dynamically routed to OpenAI models or other compatible vendors offering equivalent endpoints.

3. Unified Streaming Support Infron AI preserves the streaming semantics of the OpenAI Responses API, enabling real-time delivery of model outputs to clients—ideal for chatbots, coding assistants, or interactive tools.

4. Extended Observability and Controls By integrating request tracing, caching, and usage monitoring, Infron AI enhances the core Responses API experience with reliability and transparency features that enterprises require.

5. Developer-Friendly Integration Since Infron AI directly supports the OpenAI Responses API format, developers can integrate once and seamlessly switch between providers without rewriting client-side logic.

Quick start with Infron AI's OpenAI-compatible Responses API

Stateless Only

This 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.

Oneouter’s Responses API 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.

Base URL

https://llm.onerouter.pro/v1/responses

Authentication

All requests require authentication using your Infron AI API key:

TypeScript

const response = await fetch('https://llm.onerouter.pro/v1/responses', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer <<API_KEY>>',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'o4-mini',
    input: 'Hello, world!',
  }),
});

Python

cURL

Core Features

Basic Usage

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

Reasoning

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

Tool Calling

Integrate function calling with support for parallel execution and complex tool interactions.

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.