OpenAI API shutdown dates: o4-mini, o3-mini, o1 and GPT-4 Turbo stop working on October 23

OpenAI will shut down a batch of older models in its API on October 23, 2026, including o1, o1-pro, o3-mini, o4-mini, GPT-4 Turbo, the original GPT-4, gpt-4o-2024-05-13, gpt-4.1-nano and gpt-3.5-turbo-0125. After that date, apps that still call them stop working. The dates are on OpenAI’s deprecations page, and OpenAI says customers who are actively using a model are told by email.

More shutdowns follow in November and December, then into 2027, including GPT-5.1. Below is every upcoming date, the model OpenAI suggests in each case, and what to do now.

OpenAI models shutting down on October 23, 2026

OpenAI announced this batch on April 22, 2026, saying it wanted “to improve reliability and make it easier for developers to choose the right models”. The page lists the short names alongside the dated snapshots, so code that calls o4-mini rather than o4-mini-2025-04-16 is affected too.

From OpenAI’s deprecations page. The page also lists the “-completions” versions of GPT-3.5 Turbo, GPT-4 and GPT-4 Turbo.

Fine-tuned models built on these go on the same day: fine-tunes of GPT-3.5 Turbo, GPT-4, gpt-4.1-nano, o4-mini, babbage-002 and davinci-002. OpenAI says inference on fine-tuned models keeps working only until the base model is deprecated, and suggests rebuilding on gpt-5.6-terra, gpt-5.6-sol or gpt-5.6-luna.

The substitutes in this table are GPT-5.6 models because that was the newest family in April. For the newest deprecations, announced on October 1, OpenAI points to GPT-6 instead, so it is worth testing the GPT-6 Sol and Luna models too, which OpenAI cut prices for when it launched them.

Later OpenAI deprecation dates (November 2026 to April 2027)

From OpenAI’s deprecations page, newest notices announced October 1, 2026.

Two of these matter beyond code. Whisper is the speech-to-text model behind a lot of transcription and subtitle tools, and tts-1 powers many apps’ read-aloud voices, so tools built on them may change or need updates early next year. Agent Builder, OpenAI’s drag-and-drop tool for building agents, closes on November 30; OpenAI’s DevDay announcements show where it wants developers to go instead.

Some shutdowns have already happened this year: the Assistants API closed on August 26, 2026, the Sora 2 video models and Videos API on September 24, and gpt-3.5-turbo-instruct, babbage-002 and davinci-002 on September 28. OpenAI’s cyber model, gpt-5.4-cyber, was retired on October 1 with only 20 days’ notice.

What does deprecated mean, and how much notice do you get?

In OpenAI’s wording, a model becomes deprecated the moment the retirement is announced, and every deprecated model gets a shutdown date. “At the time of the shut down, the model or endpoint will no longer be accessible.” OpenAI uses “sunset” and “shut down” to mean the same thing. A “legacy” model is one that no longer gets updates and will probably be deprecated later.

OpenAI’s minimum notice periods are:

• Generally available models: at least six months.
• Specialised versions (chat, Codex and deep research variants): at least three months.
• Preview models (with “preview” in the name): much shorter, “such as 2 weeks”.

OpenAI can go faster “if safety or compliance concerns require” it, promising “as much notice as reasonably possible”. It also says some customers “may be able to provision dedicated capacity for continued access” after a shutdown date, by contacting its sales team.

What to do if you got the deprecation email

1. Find every place the model is named. Search your code, config files, environment variables and any no-code tools for the model names in the tables above, including short names like o4-mini and gpt-3.5-turbo.
2. Test the substitute on real work. Run the same prompts through the suggested model and compare answers, speed and cost before switching.
3. Check fine-tunes. If you rely on a fine-tuned GPT-3.5 Turbo, GPT-4, o4-mini or gpt-4.1-nano model, it goes on October 23. OpenAI is also winding down fine-tuning: since July 2 only organisations that have run a fine-tuned model in the past 60 days can start new jobs, and from January 6, 2027 no one can, so check whether you can still train a replacement.
4. Ask your software suppliers. If you pay for a tool built on OpenAI, ask which model it uses and whether it is switching before the date.
5. Switch before the deadline. After October 23, requests to these models stop working.

What isn’t affected: ChatGPT and Azure

This list is for OpenAI’s API, which developers pay for by usage. It doesn’t change what you see in the ChatGPT app: OpenAI swaps ChatGPT’s models on its own timetable and announces those changes in ChatGPT’s release notes.

If you use OpenAI models through Microsoft Azure, the dates can differ. Microsoft publishes its own Azure model retirements page, and that is the schedule that applies to Azure deployments.

Last checked: October 4, 2026, against OpenAI’s deprecations page.

Frequently asked questions

When is o4-mini being deprecated?

o4-mini is already deprecated. OpenAI shuts down o4-mini and its snapshot o4-mini-2025-04-16 in the API on October 23, 2026, and recommends gpt-5.6-terra as the substitute.

When is o3-mini being deprecated?

o3-mini and o3-mini-2025-01-31 shut down in the API on October 23, 2026. OpenAI’s suggested substitute is gpt-5.6-sol.

Is GPT-4o being deprecated in the API?

Only the gpt-4o-2024-05-13 snapshot is on OpenAI’s list, with a shutdown date of October 23, 2026. The GPT-4o audio, realtime and transcription models have their own dates in January and February 2027. Other GPT-4o models aren’t listed yet.

When is o3 being deprecated?

The o3-2025-04-16 and o3-pro-2025-06-10 snapshots shut down on December 11, 2026. OpenAI recommends gpt-5.6-sol, with reasoning mode set to pro in place of o3-pro.

When is GPT-5 being deprecated?

The original August 2025 GPT-5 snapshots (gpt-5, gpt-5-mini and gpt-5-nano dated 2025-08-07) and gpt-5-pro-2025-10-06 shut down on December 11, 2026. gpt-5.1 follows on April 1, 2027.

When is GPT-5.1 being retired?

gpt-5.1 is deprecated and will be removed from the API on April 1, 2027, along with gpt-5.3-codex. OpenAI recommends gpt-6-sol for both.

What happens when an OpenAI model is shut down?

OpenAI says that at shutdown “the model or endpoint will no longer be accessible”, so requests that still name it stop working. Any app or tool that hard-codes the model name needs updating before the date.

Does this affect ChatGPT?

No. The deprecations page covers OpenAI’s API for developers. Models in the ChatGPT app are changed separately, and OpenAI announces those in ChatGPT’s own release notes.

Does the Azure OpenAI retirement date match?

Not always. Microsoft runs its own retirement schedule for OpenAI models on Azure, so check Microsoft’s Azure model retirements page for the dates that apply there.

Sources: OpenAI (API deprecations), Microsoft (Azure OpenAI model retirements).