GPT-5.5 Thinking

OpenAI will retire GPT-5.5 and GPT-5.5 Thinking from ChatGPT and the Codex CLI on October 14, 2026, after declining developer requests on its community forum to keep the model as a legacy Codex option…

OpenAI updated GPT-5.5 Instant on June 24, improving its ability to understand user intent, maintain context across conversation turns, follow multi-part constraints, and provide better shopping and l…

OpenAI updated ChatGPT's default model to GPT-5.5 Instant in May 2026, replacing GPT-5.3 Instant for all users. The update delivers 52.5% fewer hallucinated claims and 37.3% fewer inaccurate answers, …