OpenAI Codex

What is OpenAI Codex?

OpenAI Codex is a coding agent that reads your repository, edits files, runs commands and reviews changes from the ChatGPT desktop app, a terminal CLI, IDE extensions or cloud environments. Use it for a focused fix or a code review, then check the diff. It is included in ChatGPT plans, with fewer surfaces on Free and Go.

What can you do with OpenAI Codex?

In the terminal, Codex CLI inspects files, makes edits and runs the tools installed on your machine. You choose the model, reasoning effort and permissions, and you can run a review against uncommitted changes, a commit or a base branch; the review reports findings without modifying your working tree. The codex exec command lets you use it in scripts and CI pipelines.

In an editor, the Codex extension works in VS Code, Cursor and Windsurf, and Xcode and JetBrains IDEs offer their own integrations. You can attach open files or a selection, review edits beside the code and hand a longer task to the cloud. Codex Cloud prepares an environment from your GitHub repositories, runs each task in its own workspace and lets you open a pull request when you are satisfied.

Try it on a small task

Suggested workflow: install the CLI with the command from the official documentation, open a project you know and sign in with ChatGPT. Ask Codex to explain the project, then give it one focused change with a clear result, such as a fix for a failing test. OpenAI recommends creating Git checkpoints before and after a task so you can revert changes.

Before you accept the result, run the built-in review on your uncommitted changes, read the diff yourself and run the tests. Check which commands it ran and whether it changed files outside the task. Run /status in the CLI to see how much of your usage limit the task used.

OpenAI Codex pricing and access

Codex is included in ChatGPT Free, Go, Plus, Pro, Business, Edu and Enterprise plans. On Free and Go ($8 per month) it offers GPT-6 Luna at standard speed in the desktop app, subject to rollout. Plus ($20 per month) adds Codex on the web, in the CLI, in the IDE extension and on iOS, cloud integrations such as automatic code review and Slack, and GPT-6.1 Sol. Pro costs $100, $200 or $500 per month. Business costs $20 per user per month billed annually for two or more users, or $25 billed monthly.

Limits depend on the model and task. OpenAI estimates 15 to 160 local messages per five hours with GPT-6.1 Sol on Plus, and weekly limits may also apply; cloud tasks can use more of the allowance. Plus and Pro users can buy credits when they reach their limit. With an API key you pay API prices and can use the CLI, SDK and IDE extension, but not cloud features such as GitHub code review. Codex shares usage with ChatGPT Work.