OpenAI: GPT-5.1-Codex-Max

OpenAIID: openai/gpt-5.1-codex-max

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.

Pricing per 1M Tokens

Input (Prompt)$1.25
Output (Completion)$10
Cache Read$0.13
Cache WriteFree
ImageN/A

Specifications

Context Length400K
Max Output Tokens128K
Input ModalitiesText + Image
Output ModalitiesText
TokenizerGPT
Instruct TypeN/A
Top Provider Context400K
Top Provider Max Output128K
ModeratedYes

Compare this model

See how OpenAI: GPT-5.1-Codex-Max stacks up against other models.

vs OpenAI: GPT-5.4 Nanovs OpenAI: GPT-5.4 Minivs OpenAI: GPT-5.4 Provs OpenAI: GPT-5.4vs OpenAI: GPT-5.3 Chat

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Last updated: March 23, 2026

First tracked: March 23, 2026