GPT5_4Pro
GPT-5.4 pro uses more compute to think harder and provide consistently better answers. GPT-5.4 pro is available in the Responses API only to enable support for multi-turn model interactions before responding to API requests, and other advanced API features in the future. Since GPT-5.4 pro is designed to tackle tough problems, some requests may take several minutes to finish. To avoid timeouts, try using background mode. GPT-5.4 pro supports reasoning.effort: medium, high, xhigh.
1,050,000 context window 128,000 max output tokens Aug 31, 2025 knowledge cutoff Reasoning token support