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OpenAI releases GPT-5.5 to paid ChatGPT users, then the API a day later

See how this story connects

Source: OpenAI: Introducing GPT-5.5

OpenAI released GPT-5.5, which it called its smartest and most intuitive model, to Plus, Pro, Business and Enterprise users in ChatGPT and Codex, with GPT-5.5 Pro for higher tiers, after testing with nearly 200 early-access partners. It said API deployment needed different safeguards; GPT-5.5 reached the API on 24 April with an updated system card.

Why it matters

OpenAI held API release back a day for extra safeguards, a pattern that later frontier launches followed.

When
23 Apr 2026
ID
WTA-N-2026-0164
Who
OpenAI

Summary by wheresthe.ai, from OpenAI. Checked against the source on 9 Oct 2026.

Read the original at OpenAI

Source copy: download the page text as saved on 18 Oct 2026 (PDF). Also held by the Internet Archive.

Earlier in this Storyline: What led hereOpenAI releases GPT-5.4 with native computer use and 1-million-token context

Cite this story

WTA-N-2026-0164: “OpenAI releases GPT-5.5 to paid ChatGPT users, then the API a day later.” wheresthe.ai, 23 Apr 2026. https://wheresthe.ai/d/openai-gpt-5-5-release-2026-04/ (source: OpenAI: Introducing GPT-5.5).

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