GPT 5.1 Codex Max

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gpt-5.1-codex-max

OpenAI|Created Dec 5, 2025|400k context

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GPT-5.1-Codex-Max is OpenAI’s newest agentic coding model, created for extended, high-context software development tasks. Built on an enhanced 5.1 reasoning stack, it’s been trained with agentic workflows covering software engineering, mathematics, and research. GPT-5.1-Codex-Max offers faster performance, better reasoning abilities, and increased token efficiency throughout the development process.

Overview Specifications Activity Performance Uptime Examples

Throughput

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Time-To-First-Token (TTFT)

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