OpenAI Assistants API sunset checklist

What's happening

OpenAI notified developers on August 26, 2025 that the Assistants API beta is deprecated and will be removed one year later. After the sunset date, calls to /v1/assistants, /v1/threads and related endpoints stop working. There is no announced extension.

Every date on this page is taken from the vendor's own documentation, linked under “Sources” below. Dates can change — always confirm against the source before you plan.

Migration checklist

1. Inventory every service that calls /v1/assistants, /v1/threads, /v1/runs or the file-search / code-interpreter tools — search your codebase for beta.assistants and beta.threads in the OpenAI SDKs.
2. Read OpenAI's official Assistants-to-Responses migration guide and map each Assistants concept (assistant, thread, run, tool) to its Responses / Conversations equivalent.
3. Move persistent conversation state onto the Conversations API; the Responses API is stateless per call, so anything you relied on threads to remember needs a new home.
4. Re-point file search and any hosted tools; the tool interfaces differ between the two APIs.
5. Run both integrations side by side against a test suite, compare outputs, then cut over before August 26, 2026 — leaving buffer for the usual last-week surprises.
6. Delete the old Assistants code paths once traffic is fully on Responses, so nothing silently breaks on the sunset date.

Who's affected

Anyone whose product uses OpenAI's Assistants API (v1/v2 beta) — chat assistants, retrieval-augmented tools, or agent features built on assistants, threads and runs.

Sources

• OpenAI API — Deprecations (official)
• OpenAI Developer Community — Assistants API beta deprecation announcement