GPT-5.1 Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks. The model supports building projects from scratch, feature development, debugging, large-scale refactoring, and code review. Compared to GPT-5.1, Codex is more steerable, adheres closely to developer instructions, and produces cleaner, higher-quality code outputs.
Try NowInteractive development sessions
Feature development and debugging
Large-scale code refactoring
400,000 tokens
128,000 tokens
$1.25
$10
$0.125
$15
$0.19