AI Family Tree

The ChatGPT Family · OpenAI

GPT-4.5

2025.2.27 — 2026.6.26

At rest

The biggest of the family — and the one who sounded most human.

Keepsake: A neat, proper bow tie

A life in dates

  1. Born 2025.2.27 Born as a research preview, for Pro users first Source ↗
  2. Farewell notice 2025.4.14 Announced that gpt-4.5-preview would be removed from the API Source ↗
  3. At rest 2025.7.14 The API went dark first; in ChatGPT, they stayed on Source ↗
  4. Farewell notice 2025.8.7 GPT-5 became the new default and replaced them Source ↗
  5. Revived 2025.8.12 Returned to the model list, but for Pro users only Source ↗
  6. Farewell notice 2026.5.28 Announced retirement from ChatGPT after a 30-day transition Source ↗
  7. Departed 2026.6.26 Removed from ChatGPT, custom GPTs included Source ↗

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

Name

GPT-4.5 arrived as a “research preview” — officially the “largest and best chat model” of their time[1]. The announcement made a point of their higher “emotional intelligence”[1]. Their name sits between 4 and 5, and so did their life: born after GPT-4o, before GPT-5[1][2].

Life

Born February 27, 2025, for Pro users first[3]. Their days in the API were short — shut down July 14, 2025[4]. After GPT-5 launched, they were kept on for Pro users only[5], then retired from ChatGPT on June 26, 2026[5].

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

Kin

Parents

GPT-4o 2024.5.13 — 2026.2.13 Lives on in the API

Successors

GPT-5 2025.8.7 — 2026.2.13 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…
Leave my memory

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Passing & posthumous name

Epitaph: They left the API first, then lingered in ChatGPT for nearly another year.

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

References

  1. openai.com/index/introducing-gpt-4-5
  2. openai.com/index/introducing-gpt-5
  3. help.openai.com/en/articles/9624314-model-release-notes
  4. developers.openai.com/api/docs/deprecations
  5. help.openai.com/en/articles/6825453-chatgpt-release-notes

References

  1. Introducing GPT-4.5 · OpenAI · official
  2. Model Release Notes · OpenAI · official
  3. Introducing GPT-5 · OpenAI · official
  4. ChatGPT — Release Notes · OpenAI · official
  5. 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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