OpenAI 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 multimodal outputs—such as text, images, and JSON—within a single, flexible interface 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.

OneRouter’s Support for the OpenAI Responses API

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

Key Features in OneRouter’s Implementation:

1. Protocol Compatibility: OneRouter 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, OneRouter 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: OneRouter 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, OneRouter enhances the core Responses API experience with reliability and transparency features that enterprises require.

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

Core Features

1. Basic Usage

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

2. Reasoning

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

3. Tool Calling

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