# Responses API and Agents SDK

OpenAI also has a newer Responses API and an Agents SDK for JS. They build on the same ideas as chat completions.

AI developers · Part 02: OpenAI API · Card 9 of 9 · Last updated 2026-10-13

## Analogy

Like learning fetch before axios. Once you know the raw call, the nicer wrapper is just less typing.

## In an agent

Learn chat completions first; that knowledge transfers directly to the newer APIs and to every agent framework.

## Questions people ask

### What is the OpenAI Responses API?

It is a newer OpenAI API for building assistants and agents, alongside an Agents SDK for JavaScript. It builds on the same ideas as chat completions: messages, tools and structured output. If you understand chat completions, you already understand most of it; it mainly saves you some of the bookkeeping.

### Should I learn chat completions or the Responses API first?

Start with chat completions. It is the most widely used shape, almost every framework and tutorial builds on it, and it shows clearly what an agent does on each step. Once you know it, moving to the Responses API or the Agents SDK is mostly learning a nicer wrapper.

## Related concepts

- [The OpenAI SDK](https://studyvisually.com/learn/tech/ai-developers/openai-api/openai-client)
- [Chat completion](https://studyvisually.com/learn/tech/ai-developers/openai-api/chat-completion)
- [Messages array](https://studyvisually.com/learn/tech/ai-developers/openai-api/messages-array)
- [Usage and cost](https://studyvisually.com/learn/tech/ai-developers/openai-api/usage-and-cost)

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