AI · 15 October 2026 · 5 min read
OpenAI will turn off GPT-4o and GPT-4.1 in the API on 14 January
Developers were told on 14 October. Fine-tuned copies go at the same time. The recommended replacement on the deprecation page is GPT-6 Luna. The chat product dropped these models months ago. The API had been left alone.
OpenAI’s API deprecation page says that on 14 October the company told developers it will remove a set of GPT-4 models on 14 January 2027. The list is GPT-4o, in the 6 August 2024 and 20 November 2024 snapshots, GPT-4o mini from 18 July 2024, GPT-4.1 from 14 April 2025, and GPT-4.1 mini from the same day. Fine-tuned versions shut down with the base model they were built on. The page names GPT-6 Luna as the recommended replacement for each of them.
This is the API, not the chat window. On 29 January 2026 OpenAI said it would retire GPT-4o, GPT-4.1 and related models from ChatGPT on 13 February, and it said then that the API was not changing. The January shutdown of the chat product and this January shutdown of the programming interface are nine months apart. A product that still calls gpt-4o-2024-11-20, or a fine-tune sitting on GPT-4.1, has a date. After 14 January that call is scheduled to fail.
Three months is the notice
The page does not say how many applications still use these models, what they cost relative to GPT-6 Luna, or whether a fine-tune can be moved without retraining. It also does not say the chat product is affected again. A robotics or vision team that parked an older model behind a tool, because it was cheap or because a workflow was written for it, is the reader who has to check. The newer models already on this desk, including GPT-6, are not the ones being removed.
A shutdown date is a fact a developer can plan around. It is not a claim that the replacement behaves the same way on the same prompts. Anyone who depends on a particular refusal, a particular tone, or a fine-tune trained on GPT-4.1 has to test Luna before January, not after the old endpoint goes dark. OpenAI’s notice is the calendar. The difference in the answers is still the caller’s to measure.