Coding
Codex
OpenAI's coding agent, available in ChatGPT, the cloud, a CLI, IDE extensions and a desktop app, for building, reviewing and shipping software.
Codex is OpenAI’s coding agent. OpenAI presents it as an “AI coding partner” for engineering work that spans planning and building features, refactoring, bug hunting, code review and releases.
The current product grew from two 2025 launches. In April 2025 OpenAI released Codex CLI, an open-source coding agent that runs in the terminal. On 16 May 2025 it introduced Codex as “a cloud-based software engineering agent that can work on many tasks in parallel,” available first to ChatGPT Pro, Business and Enterprise users and powered by a version of its o3 reasoning model tuned for software engineering.
Today Codex is offered across several surfaces tied to one ChatGPT account: Codex in ChatGPT, a cloud mode that keeps tasks running when a laptop is closed, an IDE extension, the CLI, a desktop app for running agents in parallel, and automated pull request review. Plugins connect it to GitHub, Slack, Gmail, Google Drive, Figma, Notion and Supabase. It runs on OpenAI’s own models. Codex is also available as a third-party agent inside GitHub Copilot.
Codex is aimed at software engineers and development teams, from individual developers to businesses that need shared workspaces and admin controls. It is included in ChatGPT Plus, Pro and Business plans, with usage limits that scale by tier, rather than sold separately. OpenAI’s Codex page links to the ChatGPT pricing section for current plan details; see chatgpt.com/pricing.