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by OpenAI
Foundational reasoning model trained with reinforcement learning to think step-by-step before responding. Forms rich internal chains of reasoning to tackle complex problems in mathematics, coding, and scientific domains with thoughtful deliberation.
- Deep reasoning foundation using reinforcement learning for step-by-step problem analysis
- Rich internal reasoning chains forming thoughtful deliberation before delivering answers
- Complex problem specialization excelling in mathematics, coding, and scientific challenges
- Multimodal reasoning support handling both text and visual inputs with analytical depth
- Established reasoning benchmark serving as the foundation for OpenAI's reasoning model development
Model Information
Supported Formats
GPT 5.5OpenAI's most advanced model released April 2026. GPT-5.5 is recommended for most reasoning workloads, combining frontier intelligence with configurable reasoning effort (none → xhigh). Available in API, Codex, and ChatGPT.
GPT 5.5 ProHighest-intelligence API option in the GPT-5.5 family. Use for the most challenging problems that require maximum reasoning depth and can tolerate higher latency. Supports full reasoning effort range from none to xhigh.
GPT 5.4GPT-5.4 is OpenAI's frontier model for complex professional work, designed for agentic, coding, and professional workflows with the highest reasoning capability. Features a 1.05M token context window, native computer use, and built-in support for web search, file search, and MCP.