Tool·AI Models & Capabilities·Added 7 days ago

GPT-5.5

Also known as: GPT 5.5, OpenAI GPT-5.5

OpenAI's frontier model released in late April 2026, notable for a 60 percent reduction in hallucinations compared to its predecessor and native computer use. It became the default model for OpenAI API users on April 24, 2026.

GPT-5.5 shipped on April 23, 2026, with API access rolling out the following day. For builders, the headline number is a claimed 60% reduction in hallucinations relative to GPT-5.4, which matters more for production reliability than synthetic benchmark scores. It also ships with native computer use capability, meaning the model can take actions in a browser or desktop environment rather than only generating text.

The release landed during what observers called the most concentrated week of frontier model launches in the industry's history, with OpenAI, Anthropic, DeepSeek, and Microsoft all making major announcements in rapid succession. GPT-5.5 competes directly with Claude Opus 4 and Gemini 3.5 at the frontier tier.

For teams with existing API pipelines, the GPT-5.5 launch triggered a necessary review. OpenAI retired the GPT-5.1 line in March 2026, and the shift to GPT-5.4 as the intermediate default, then 5.5, changed tokenizer behavior and cost structures. Builders who automated on earlier models without version-pinning saw unexpected output changes.

This definition is AI-generated and refreshed weekly. It may contain inaccuracies. Use your own judgment, especially for production decisions.

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