OpenAI and Anthropic detail model retirement timelines

OpenAI will shut down about 50 model snapshots between September 24 and December 11, 2026, including GPT-4, GPT-3.5-turbo and Sora 2. Anthropic retired nine Claude models in twelve months. Both vendors use four lifecycle states: active, legacy, deprecated and retired.

• OpenAI promises at least 6 months notice for general models and 3 months for specialised variants
• Anthropic guarantees at least 60 days, and its recent retirements landed near that window
• A pinned snapshot fails loudly with a 404 model_not_found, while an alias upgrades silently
• Anthropic keeps weights of every public model but does not commit to releasing them