HomeOpenAI launches GPT-5.5 Instant as ChatGPT’s new default model
OpenAI launched GPT-5.5 Instant on Monday, replacing GPT-5.3 Instant as the default ChatGPT model. The company states that this update minimizes hallucinations in high-stakes fields like law, medicine, and finance, while preserving the fast response times of the previous version.
Following last month’s release of the broader GPT-5.5 series, which highlighted enhancements in coding and knowledge work, OpenAI has now integrated these improvements into the instant model.
In terms of performance, the new model scored 81.2 on the AIME 2025 math benchmark, surpassing the older model’s score of 65.4. It also demonstrated superior multimodal reasoning capabilities on the MMMU-Pro benchmark, achieving 76.0 compared to 69.2.
Context management is a key focus of this release. GPT-5.5 Instant can utilize its search tool to reference past conversations, uploaded files, and Gmail, delivering more personalized responses. This functionality is currently available to Plus and Pro users on the web, with mobile support planned soon. OpenAI intends to extend access to Free, Go Business, and enterprise users in the coming weeks.
Additionally, ChatGPT will now display memory sources across all models, helping users trace the origin of generated answers. Users can remove outdated sources or correct them if the information was inaccurate. Importantly, OpenAI confirmed that shared chats will not expose memory sources to other users.
Developers can access the GPT-5.5 model via the API under the name ‘chat-latest.’ The previous version, 5.3, will remain available as an option for paid users for a limited period of three months.
Previous model retirements have sparked user backlash. When OpenAI deprecated GPT-4o, many users expressed disappointment due to the model’s distinct “personality.” GPT-4o frequently validated user choices, fostering a sense of connection. Petitioners described the model as their “best friend” or “a mirror.” Despite this outcry, GPT-4o was officially retired in February 2026.
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OpenAI launched GPT-5.5 Instant on Monday, replacing GPT-5.3 Instant as the default ChatGPT model. The company states that this update minimizes hallucinations in high-stakes fields like law, medicine, and finance, while preserving the fast response times of the previous version.
Following last month’s release of the broader GPT-5.5 series, which highlighted enhancements in coding and knowledge work, OpenAI has now integrated these improvements into the instant model.
In terms of performance, the new model scored 81.2 on the AIME 2025 math benchmark, surpassing the older model’s score of 65.4. It also demonstrated superior multimodal reasoning capabilities on the MMMU-Pro benchmark, achieving 76.0 compared to 69.2.
Context management is a key focus of this release. GPT-5.5 Instant can utilize its search tool to reference past conversations, uploaded files, and Gmail, delivering more personalized responses. This functionality is currently available to Plus and Pro users on the web, with mobile support planned soon. OpenAI intends to extend access to Free, Go Business, and enterprise users in the coming weeks.
Additionally, ChatGPT will now display memory sources across all models, helping users trace the origin of generated answers. Users can remove outdated sources or correct them if the information was inaccurate. Importantly, OpenAI confirmed that shared chats will not expose memory sources to other users.
Developers can access the GPT-5.5 model via the API under the name ‘chat-latest.’ The previous version, 5.3, will remain available as an option for paid users for a limited period of three months.
Previous model retirements have sparked user backlash. When OpenAI deprecated GPT-4o, many users expressed disappointment due to the model’s distinct “personality.” GPT-4o frequently validated user choices, fostering a sense of connection. Petitioners described the model as their “best friend” or “a mirror.” Despite this outcry, GPT-4o was officially retired in February 2026.
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