Update on April 16, 2025: We launched Codex CLI, our new open source local coding agent. To get started, please visit https://github.com/openai/codex⁠(opens in a new window).

The OpenAI Codex models were deprecated⁠(opens in a new window) in March 2023. To learn about our latest coding models, please visit our docs⁠(opens in a new window).

Codex is the model that powers GitHub Copilot⁠(opens in a new window), which we built and launched in partnership with GitHub a month ago. Proficient in more than a dozen programming languages, Codex can now interpret simple commands in natural language and execute them on the user’s behalf—making it possible to build a natural language interface to existing applications. We are now inviting businesses and developers to build on top of OpenAI Codex through our API.

OpenAI Codex is a descendant of GPT‑3; its training data contains both natural language and billions of lines of source code from publicly available sources, including code in public GitHub repositories. OpenAI Codex is most capable in Python, but it is also proficient in over a dozen languages including JavaScript, Go, Perl, PHP, Ruby, Swift and TypeScript, and even Shell. It has a memory of 14KB for Python code, compared to GPT‑3 which has only 4KB—so it can take into account over 3x as much contextual information while performing any task.