GPT-5.1 Codex Max

Retired

OpenAI · December 2025

OpenAI retired this model on 23 July 2026, so you can't start new chats with it. Use GPT-5.6 Sol instead. Your previous conversations are still available.

Built for programming tasks that run a long time on their own.

Best for: Coding, deep reasoning, and agent workflows
Use instead: GPT-5.6 Sol

Context window
400,000 tokens
≈ 300,000 words · about 1,200 pages
Max output
128,000 tokens
≈ 96,000 words in a single answer
Knowledge cutoff
September 2024
its training cutoff

Modalities

TextInput and output
ImageInput only
AudioNot supported
VideoNot supported

Reasoning effort

Low
Medium
High
X-High

Features

StreamingSupported
Function callingSupported
Structured outputsSupported
Fine-tuningNot supported

Ready to try it?

Polymeti is currently invite-only.

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