Assistants API

The programmatic interface for building persistent, stateful AI assistants with built-in tools like Code Interpreter and Retrieval (Note: Deprecated; migrate to Responses API).

The Assistants API provides a managed conversational infrastructure, abstracting complex state management and enabling persistent, multi-turn interactions. Developers use it to create intelligent agents with custom instructions and powerful tools: Code Interpreter for data analysis, Retrieval for knowledge base integration, and Function Calling for external API interaction. While powerful, this API is now deprecated; all new development must target the simpler, more flexible Responses API for improved performance and features. Plan your migration now: the Assistants API shuts down August 26, 2026.

https://platform.openai.com/docs/assistants/overview