OpenAI is shutting down custom GPTs — the build-your-own chatbots it introduced in late 2023 — and replacing them with a plugins-and-skills system. Its help center says custom GPTs are scheduled to retire on December 11, 2026, across every ChatGPT plan, and creation of new GPTs ends on October 26. Some Enterprise workspaces with an approved deferral get until February 11, 2027.

A migration tool moves a GPT's instructions into a skill inside a new plugin, copies knowledge files as reference material, and carries connected apps along. But much is lost in translation: custom actions (API calls) don't transfer at all and may need a custom MCP server to rebuild; the chosen model doesn't carry over; past conversations don't migrate; sharing settings reset to private; and only the latest published version transfers, so unpublished drafts die.

Google is making a parallel move: it's converting Gemini's Gems into skills starting November 17. Both labs are clearly converging on modular components — skills, apps, connected tools that load on demand — and away from single-purpose custom assistants. If you built a GPT for work or customers, publish its final version before October 26.