GPT-5.5 Instant: smarter, clearer, and more personalized

OpenAI has updated ChatGPT's default model to GPT-5.5 Instant, rolling out to all users to replace GPT-5.3 Instant and serving as chat-latest in the API. According to OpenAI, internal evaluations show the new model produces 52.5 percent fewer hallucinated claims on high-stakes prompts covering medicine, law, and finance compared to its predecessor, alongside a 37.3 percent reduction in inaccurate claims on challenging user conversations. GPT-5.5 Instant provides tighter, more concise answers, reduces verbosity and overformatting, and improves capabilities in analyzing images, answering STEM questions, and utilizing web search. Additionally, OpenAI is introducing enhanced personalization leveraging past chats, files, and connected Gmail, allowing the model to more effectively reference context for tailored suggestions. Accompanying these personalization updates are new memory sources across all consumer plans on the web, giving users visibility over the context used to personalize responses with options to delete or correct outdated information. Paid users will retain access to GPT-5.3 Instant through model configuration settings for three months before it is retired, while personalization rollouts and memory sources are expanding across various tiers and platforms.