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Availability · April 23, 2026

GPT-5.5 launches

OpenAI introduced GPT-5.5 for ChatGPT and Codex, focusing on coding, research and multi-step tool use.

Why it matters

For these models, practical value depends on carrying work through to a checked result.

Rollout began April 23. A separate April 24 update to the source reports API availability.

Event record

Event date: April 23, 2026
Timeline date: Event date
Verification: Sources gathered automatically · September 11, 2026
ID: evt-0026

Sources

primary Introducing GPT-5.5
OpenAI · Published April 23, 2026

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