OpenAI Responses API

Status: Production Ready Last Updated: 2026-01-21 API Launch: March 2025 Dependencies: openai@6.16.0 (Node.js) or fetch API (Cloudflare Workers)

What Is the Responses API?

OpenAI's unified interface for agentic applications, launched March 2025. Provides stateful conversations with preserved reasoning state across turns.

Key Innovation: Unlike Chat Completions (reasoning discarded between turns), Responses preserves the model's reasoning notebook, improving performance by 5% on TAUBench and enabling better multi-turn interactions.

vs Chat Completions: