Announced as a first-party product at OpenAI DevDay on September 29, 2026, Sign in with ChatGPT covers identity (create, link, or access a partner account with ChatGPT credentials; available globally) and eligible plan usage (Plus and Pro allowance inside participating tools, counting toward existing ChatGPT plan limits, with per-app caps). It is distinct from unofficial June 2026 Codex device-auth wrappers and from ChatGPT's cloud-browser sign-in to third-party websites.