OpenAI quietly switched ChatGPT's default to GPT‑5.5 Instant

OpenAI said on May 5 that it had updated ChatGPT’s default model to GPT-5.5 Instant, replacing GPT-5.3 Instant for everyday use in the chatbot. The company also introduced `chat-latest`, an API model alias that points to “the latest Instant model currently used in ChatGPT,” according to OpenAI’s developer documentation. OpenAI said the underlying snapshot behind that alias “will be regularly updated,” making it a moving target rather than a dated, fixed model name. ### When did OpenAI make the switch? OpenAI published the GPT-5.5 Instant update on May 5, 2026, in a product post that said it was “updating ChatGPT’s default model, available to everyone.” A separate Help Center release note said GPT-5.5 Instant was rolling out as ChatGPT’s new default model and that it replaced GPT-5.3 Instant for all ChatGPT users. (openai.com) OpenAI’s Help Center also said that, as of February 13, 2026, ChatGPT had already retired GPT-5 Instant and GPT-5 Thinking. By default, all users now have access to GPT-5.5 models, while paid tiers can manually choose GPT-5.5 Instant or GPT-5.5 Thinking in the model picker. ### What exactly is `chat-latest`? OpenAI’s API model page describes `chat-latest` as the “latest Instant model used in ChatGPT.” The same page says OpenAI recommends using GPT-5.5 directly for production API workloads, while offering `chat-latest` for developers who want to test the current ChatGPT-style Instant model. (openai.com) (help.openai.com) OpenAI’s API changelog said on May 5 that the company released a `chat-latest` snapshot pointing to the latest Instant model currently used in ChatGPT. The changelog added that the underlying snapshot “will be regularly updated,” which means developers using the alias should expect behavior to change as OpenAI refreshes the ChatGPT default. (developers.openai.com) ### How is that different from older chat model names? OpenAI’s API docs distinguish between aliases and snapshots. Older model pages such as `gpt-5.3-chat-latest` pointed to a specific GPT-5.3 Instant snapshot used in ChatGPT, while `chat-latest` is tied to whatever Instant model ChatGPT is currently running. OpenAI’s deprecations page said on May 8 that developers using `gpt-5.2-chat-latest` and `gpt-5.3-chat-latest` had been notified of their deprecation, with removal scheduled for August 10, 2026. (developers.openai.com) OpenAI listed GPT-5.5 as the recommended replacement for both. ### What did OpenAI say improved in GPT-5.5 Instant? OpenAI said GPT-5.5 Instant delivered “smarter, more accurate answers” with “clearer, more concise” responses and better personalization. (developers.openai.com) In internal evaluations, the company said GPT-5.5 Instant produced 52.5% fewer hallucinated claims than GPT-5.3 Instant on high-stakes prompts in medicine, law and finance, and reduced inaccurate claims by 37.3% on especially difficult conversations that users had flagged for factual errors. (developers.openai.com) OpenAI’s release notes said the new default also improved image understanding, STEM performance and the model’s handling of cases where ChatGPT decides to search the web. The product post said the update was aimed at the “daily driver” experience for ChatGPT’s broad user base. ### What should developers watch next? (openai.com) OpenAI released GPT-5.5 and GPT-5.5 Pro to the API on April 24, one day after announcing GPT-5.5 on April 23. The company’s API guide says GPT-5.5 is the latest model family and recommends treating it as a fresh migration target rather than carrying over prompt setups unchanged from older versions. August 10, 2026, is the next dated milestone in OpenAI’s documentation. (help.openai.com) That is the scheduled shutdown date for `gpt-5.2-chat-latest` and `gpt-5.3-chat-latest`, according to the company’s deprecations page, while `chat-latest` remains the alias for the current Instant model used in ChatGPT. (developers.openai.com) (openai.com)