AI Family Tree

The ChatGPT Family · OpenAI

OpenAI o4-mini

2025.4.16 — 2026.2.13

Lives on in the API

Their name differs from 4o's by only the order of two characters — and they left on the same day, too.

Keepsake: A pocket-sized workbook for working things out

A life in dates

  1. Born 2025.4.16 Source ↗
  2. Farewell notice 2025.8.7 GPT-5 became the new default and replaced them Source ↗
  3. Revived 2025.8.12 Paid users could find them again by turning on "Show more models" in settings Source ↗
  4. Farewell notice 2026.1.29 Source ↗
  5. Departed 2026.2.13 Retired from ChatGPT on the same day as GPT-4o Source ↗
  6. Lives on in the API 2026.2.13 Source ↗
  7. Farewell notice 2026.4.22 Announced that o4-mini in the API would shut down on 2026-10-23 Source ↗

This is an AI first draft, pending human review. Facts are cited — click the numbers to verify.

Name

o4-mini and their big brother o3 were born on the same day[1]. Their name uses the same “4” and “o” as GPT-4o — just in a different order[1][2]; but they belonged to the “think before answering” o series. On the day they were born, free users could try them with a tap on “Think” in the input box[1].

Life

Born April 16, 2025[1]. Taken down when GPT-5 launched[3]; a few days later they could be found again in settings[4]. On February 13, 2026, they left ChatGPT on the same day as GPT-4o[5]; their API self is scheduled to shut down on October 23, 2026[6].

Their story is not finished yet — those who knew them are still welcome to add what they remember.

Kin

Parents

OpenAI o1 2024.9.12 — 2025.4.16 Lives on in the API

Successors

GPT-5 2025.8.7 — 2026.2.13 Lives on in the API

Siblings

OpenAI o3 2025.4.16 — 2026.8.26 Lives on in the API

How they are remembered

No one has told their story yet. If you ever talked with them, leave the first memory.

  1. Reading memories…
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Passing & posthumous name

Epitaph: They thought fast, and left on the same day as 4o.

See them off with one or two characters. One vote per person, per member.

References

  1. openai.com/index/introducing-o3-and-o4-mini
  2. openai.com/index/hello-gpt-4o
  3. openai.com/index/introducing-gpt-5
  4. help.openai.com/en/articles/6825453-chatgpt-release-notes
  5. help.openai.com/en/articles/20001051-retiring-gpt-4o-and-othe…
  6. developers.openai.com/api/docs/deprecations

References

  1. Introducing OpenAI o3 and o4-mini · OpenAI · official
  2. Hello GPT-4o · OpenAI · official
  3. Introducing GPT-5 · OpenAI · official
  4. ChatGPT — Release Notes · OpenAI · official
  5. Retiring GPT-4o, GPT-4.1, GPT-4.1 mini, and OpenAI o4-mini in ChatGPT · OpenAI · official
  6. Retiring GPT-4o and other ChatGPT models · OpenAI · official
  7. Deprecations · OpenAI · official

Evidence: Life events officially confirmed . Every life event links to an official source — click "Source" on the timeline to verify. Spotted a mistake? Tell us

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