What is the context window of GPT-5.1 Codex?

GPT-5.1 Codex has a context window of 400K tokens.

When was GPT-5.1 Codex released?

GPT-5.1 Codex was released on 2025-12-01.

Name: GPT-5.1 Codex
Author: OpenAI

gpt-5.1-codex

ProprietaryMultimodal

GPT-5.1-Codex is a coding-specialized version of GPT-5.1, optimized for software engineering and agentic coding workflows at 400K context.

GPT-5.1 Codex has a 400K-token context window.

VisionMultimodalReasoningFunction CallingTool UseStructured OutputsCode ExecutionPrompt CachingBatch APIAudioFine-tuning

Released2025-12-01

Context400K

ArchitectureDecoder Only

Specializationcode

LicenseProprietary

Trainingpretrained

Cutting-edge research and development.

San Francisco, California, United States

Founded 2015