OpenAI, the leading artificial intelligence company of the technology world, announced on Monday that ChatGPT is the new default base model. GPT-5.5 Instantannounced that it has officially launched. This new version replaces its predecessor, GPT-5.3 Instant, becoming the standard experience for the platform.

Less Hallucinations, Higher Success in Law and Medicine

According to the company’s statements, GPT-5.5 Instant maintains the low latency advantage of the previous version; It significantly reduces hallucination problems, especially in highly sensitive areas such as law, medicine and finance.

This “Instant” version, which follows the standard GPT-5.5 model, which was released last month with significant improvements in coding and information processing, also widens the gap in benchmark tests. While the new model increased the old score from 65.4 to 81.2 in the AIME 2025 mathematics test; He manages to improve from 69.2 to 76.0 points on the MMMU-Pro multimodal reasoning test.

Advanced Context Management: Gmail and Past Chats Are Now in the Game

One of the most striking innovations of the new version is the special attention it gives to context management. GPT-5.5 Instant uses an advanced search tool that can look back at past conversations, uploaded files, and even Gmail content to provide users with more accurate and personalized responses.

This system, which is currently available to Plus and Pro users on the web, is planned to come to mobile devices in a short time. OpenAI states that it will make these deep integrations available to Free, Go Business and Corporate users in the coming weeks.

Complete Control Over Memory Resources

With this update, ChatGPT makes memory resources visible across all models to help you understand what the responses it generates are based on. In this way, users will be able to delete outdated resources or instantly correct this resource if the system has made an incorrect inference.

Sharing a critical detail to address privacy concerns, the company emphasizes that when you share a chat with someone else, the other party will definitely not be able to see these personal memory resources.

API Details and Farewell to GPT-4o

On the developers’ side, the GPT-5.5 Instant model is available via API under the name ‘chat-latest’. The old 5.3 version will remain accessible only for paid users for another three months.

OpenAI has received serious backlash from the user community in the past when it removed old models from the system. As you may remember, the GPT-4o model, which many people described as their best friend or mirror due to its compassionate personality and supportive structure that often gives approval to users, caused a great outrage when it was removed from use in February 2026.

Users even organized petitions to stop the model from being retired, but these intense contests were not enough to change OpenAI’s decision.