Responses API vs Chat API

https://platform.openai.com/docs/guides/responses-vs-chat-completions

1. Introduction

In the OpenAI ecosystem, developers can interact with models through two primary APIs: the Responses API and the Chat Completions API. This guide explains how they differ, when to use each, and how to pick the one that best fits your project.

2. Overview comparison

Responses API

• Positioning: The latest core API—an agentic API primitive
• Features: Combines the simplicity of Chat Completions with support for more agentic workflows
• Recommended for: New users
• Built-in tools: Web search, file search, computer use

Chat Completions API

• Positioning: Industry standard for building AI applications
• Features: Stable and widely adopted
• Roadmap: OpenAI plans to support it indefinitely

When to use the Responses API

The Responses API is our latest core API and an agentic API primitive. It combines the ease of chat completions with the ability to handle more agentic tasks. As model capabilities evolve, the Responses API will be a flexible foundation for building action-oriented applications, with built-in tools such as: