OpenAI: GPT-5.1-Codex-Max

openai/gpt-5.1-codex-max

Created Dec 4, 2025400,000 context

$1.25/M input tokens$10/M output tokens

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic workflows spanning software engineering, mathematics, and research. GPT-5.1-Codex-Max delivers faster performance, improved reasoning, and higher token efficiency across the development lifecycle.

OpenAI: GPT-5.1-Codex-Max

openai/gpt-5.1-codex-max

Created Dec 4, 2025400,000 context

$1.25/M input tokens$10/M output tokens

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic workflows spanning software engineering, mathematics, and research. GPT-5.1-Codex-Max delivers faster performance, improved reasoning, and higher token efficiency across the development lifecycle.

Recent activity on GPT-5.1-Codex-Max

Total usage per day on OpenRouter

Prompt

681M

Reasoning

6.77M

Completion

6.31M

Prompt tokens measure input size. Reasoning tokens show internal thinking before a response. Completion tokens reflect total output length.