OpenAI Responses API

Status: Production Ready Last Updated: 2025-10-25 API Launch: March 2025 Dependencies: openai@5.19.1+ (Node.js) or fetch API (Cloudflare Workers)

What Is the Responses API?

The Responses API (/v1/responses) is OpenAI's unified interface for building agentic applications, launched in March 2025. It fundamentally changes how you interact with OpenAI models by providing stateful conversations and a structured loop for reasoning and acting.

Key Innovation: Preserved Reasoning State

Unlike Chat Completions where reasoning is discarded between turns, Responses keeps the notebook open. The model's step-by-step thought processes survive into the next turn, improving performance by approximately 5% on TAUBench and enabling better multi-turn interactions.

Why Use Responses Over Chat Completions?