OpenAI releases GPT-5.5 Instant, a new default model for ChatGPT

On Tuesday, OpenAI released a new foundational model called GPT-5.5 Instant. This replaces GPT-5.3 Instant as the default ChatGPT model. The company said the model reduces hallucinations in sensitive areas such as law, medicine, and finance, while maintaining the low latency of its predecessor.

OpenAI released its latest GPT-5.5 model last month, claiming improvements in areas such as coding and knowledge work.

The new model also achieved a score of 81.2 on the AIME 2025 math test, compared to the previous model’s score of 65.4. It also outperformed its predecessor on the MMMU-Pro multimodal inference benchmark with a score of 76 to 69.2.

This release has a special focus on context management. GPT-5.5 Instant can use search tools to browse past conversations, files, and Gmail to provide more personalized answers. The feature is now available to Plus and Pro users on the web and will be rolling out to mobile soon. OpenAI said it plans to expand access to this feature to Free, Go Business, and Enterprise users in the coming weeks.

With this update, ChatGPT will also show you the memory source for all your models, allowing you to understand where they generated their answers from. Users can delete old sources or correct answers if they are incorrect. Importantly, the company said that if you share a chat with someone, that person won’t be able to see the memory source.

For developers, the GPT-5.5 model is available as “chat latest” through the API, and 5.3 is only available for three months as an option for paid users.

The company is facing backlash over its move to withdraw previous models. When OpenAI withdrew the GPT-4o model, there was a huge backlash from users related to the model’s “personality”. GPT-4o frequently affirmed the user’s choice and made the user feel connected to that particular model. Users who signed a petition to stop OpenAI from being phased out described the model as their “best friend” or “mirror.” Despite protests, GPT-4o was deprecated in February 2026.