Codex

Codex CLI is OpenAI's coding agent for the terminal, written in Rust and released under Apache 2.0. Installation is a shell script on macOS, Linux and Windows, or npm install -g @openai/codex, or a Homebrew cask, and running codex starts a session in the current project. The same agent turns up elsewhere: an IDE extension for VS Code, Cursor and Windsurf, a desktop app through codex app, and a separate cloud version called Codex Web. Signing in with a ChatGPT account folds usage into a Plus, Pro, Business, Edu or Enterprise plan; an API key works too, with extra setup.