Assistant API

The original persistent object for building custom AI agents: deprecated, migrate your integration to the Responses API now.

The Assistants API was the persistent object for creating stateful AI agents: it bundled the model, instructions, and tools like File Search (RAG), Code Interpreter, and Function Calling into a single configuration. This simplified complex workflows, notably for knowledge retrieval. However, the Assistants API is now deprecated, shutting down completely on August 26, 2026. Transition your integration to the new Responses API immediately: it offers a simpler, more flexible mental model with better performance and new features.

https://platform.openai.com/docs/assistants-migration-guide