OpenAI Announces GPT-5.5 Retirement From ChatGPT

The same day, the OpenAI Developers account quoted the post and drew a line. The single sentence read, "GPT-5.5 will remain available via the OpenAI API Platform and in Codex sessions authenticated with an API key." The retirement applies only to products used while logged in with a ChatGPT account; the path where developers call the model directly through the API stays as it is. That post passed 160,000 views.

The deprecation list in OpenAI's developer documentation, which METAL reviewed, did not include GPT-5.5 as of September 16. The document lays out the minimum notice OpenAI gives before retiring API models: at least 6 months for generally available models, at least 3 months for specialized variants such as chat or Codex versions, and possibly much shorter, such as 2 weeks, for preview models. It adds that when safety or compliance concerns require a faster retirement, the company gives as much notice as reasonably possible. That promise, however, is about the API; swapping models inside the ChatGPT app falls outside the document's scope.

Seen through a tech lawyer's eyes, what matters in this announcement is not the date but the boundary. The same GPT-5.5 gets a 6-month notice policy under an API contract and goes away 29 days after the announcement under a consumer subscription. That is the span from the September 15 announcement to the October 14 retirement. OpenAI's Help Center model release notes show that retirements inside ChatGPT have long moved separately from the API. In a May 28 notice the company retired o3 from ChatGPT after a 90-day sunset period and GPT-4.5 after a 30-day one, and wrote at the time, "These changes apply to ChatGPT only; there are no changes to the API." The three GPT-5.1 models disappeared from ChatGPT on March 11, with existing conversations continuing automatically on successor models.

GPT-5.5's own trajectory is in those release notes. On May 28 OpenAI said it had updated GPT-5.5 Instant in ChatGPT and the API to be easier to read, more natural in conversation, and less prone to overly long responses, and on the same day it removed canvas from GPT-5.5 Instant and GPT-5.5 Thinking. Then on July 9, GPT-5.6 Sol entered ChatGPT for paid plans. METAL reported in August on the GPT-5.6 Sol improvements and the assignment of Luna to free users, and on September 3 covered the release of GPT-6 Astra. According to reports, GPT-5.5 was released on April 23, which means it leaves ChatGPT without completing six months.

The pushback predates the announcement. On the OpenAI developer community, a Pro subscriber writing as Aurex posted a request to keep GPT-5.5 in Codex as a legacy option. Describing himself as someone who works in Codex daily, he argued that GPT-5.5 is fast, consistent, and follows instructions closely with little rework, whereas GPT-5.6 Sol, despite leading on benchmarks, over-reasons on routine development tasks, expands the scope of requests, and uses more time and quota. "Sol is also not a drop-in replacement," he wrote, adding that when Sol launched, a large number of experienced Codex users voluntarily switched back to GPT-5.5.

The post cites GitHub issue numbers as evidence: a side-by-side test on identical hardware, prompts, and tool access in which GPT-5.5 triggered web search and completed the workflow in all three runs while Sol and Terra never invoked search; reports that Sol slows down simple tasks by adding sub-agents and delegation steps; and cases where GPT-5.6's tool calling fails entirely in the same environment. The author acknowledged that some of these failures may come from the Codex harness or tool implementations rather than the model, but said the distinction is irrelevant to paying users, who use the whole product rather than a model. He asked for four things: keeping the model as a legacy option even with usage caps, delaying retirement until a successor matches it on real-world work, evaluating replacements on complete development workflows rather than benchmarks, and a minimum of 90 days of advance notice.

Translated into the language of legal documents, this request is about trust, not contract. The subscription terms contain no promise to keep a particular model, and the company's published notice policy applies only to the API. So the only thing ChatGPT users can lean on is the practice the company has set for itself, and this time that practice was 29 days. The developer account's prompt confirmation that the API path stays open is a sign it knows exactly where that line falls. For anyone who will miss GPT-5.5 in ChatGPT, the one open road is logging in to Codex with an API key, and that road runs through an API account rather than a ChatGPT subscription. As the author put it, "newer does not automatically mean fully replaced," and that sentence sits at the center of this retirement debate. OpenAI put out the October 14 date and the API exit together, and the 29 days in between are the time it has given users to move their workflows.