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OpenAI

GPT-5.5

OpenAI•Documentation
gpt-5.5
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OpenAI's first fully retrained base model since GPT-4.5. Features 1.05M token context window, ~40% improved token efficiency, and reasoning defaulted to 'low' (rather than 'none') for stronger out-of-the-box answers. Same reasoning controls as GPT-5.4 — 'none' through 'xhigh' available.

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Chat
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Prompts
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Playgrounds
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Workflows
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Context Window
1048K
tokens
Max Output
128,000
tokens
Web Search
Available
Structured Output
Available

Supported File Formats

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