O3 — Simon Carter

developer tools apis category

Developer Tools & APIs

Two OpenAI shutdowns land on 26 August 2026: o3 leaves ChatGPT and the Assistants API is gone for good

On 26 August 2026, OpenAI removes o3 from ChatGPT's model picker and permanently shuts down the Assistants API. Here's what breaks and what to do.

23 August 2026

models assistants category

Models & Assistants

OpenAI is retiring o3 from ChatGPT on 26 August 2026

OpenAI has set 26 August 2026 as the hard retirement date for o3 in ChatGPT, following a 90-day sunset period announced on 28 May 2026.

8 August 2026

models assistants category

Models & Assistants

OpenAI is retiring GPT-4.5 and o3 from ChatGPT — here's what changes and when

GPT-4.5 leaves ChatGPT on June 27, 2026 and o3 on August 26. No API changes. Here's what it means for you.

Updated 7 July 2026