OpenAI's GPT-5.5 Instant Becomes New ChatGPT Default

OpenAI has launched GPT-5.5 Instant as the new default ChatGPT model, replacing GPT-5.3 Instant. The update reduces hallucinations in law, medicine, and finance, improves math and multimodal reasoning benchmarks, and introduces personalized context management by referencing past conversations, files, and Gmail. The memory feature launches for Plus and Pro users on web, with broader rollout planned. ChatGPT will also display memory sources across all models, letting users delete or correct them. Developers can access GPT-5.5 via API as chat-latest, while GPT-5.3 remains available to paid users for three more months.