What is OpenAI Codex?
Codex is OpenAI's AI coding agent. It can answer questions about a codebase, write features, fix bugs, refactor code and review changes, working either locally on your machine or on tasks that run in the cloud.
You can use Codex from a command-line tool, an IDE extension, a desktop app and the web through ChatGPT. It is included with ChatGPT plans, including a limited Free tier, and can also run with an OpenAI API key.
OpenAI Codex key features
- 01
Local and cloud tasks
Work interactively in your terminal or editor, or hand off tasks that run in the cloud while you keep coding.
- 02
Code review
Review changes and pull requests to catch bugs before they are merged.
- 03
Parallel work
Run several tasks at once and review each result separately.
- 04
Works with ChatGPT
Uses your ChatGPT sign-in and plan, so there is no separate subscription to manage.
Is OpenAI Codex right for you?
Best for
- Developers already paying for ChatGPT who want an agent included
- Delegating well-scoped tasks to run in the cloud
- Getting a second pair of eyes on pull requests
Things to consider
- Usage limits are shared with other ChatGPT agent features and vary by plan.
- Some features roll out gradually, so availability can differ between plans.
- Cloud tasks need your repository connected, so check your organisation's policies first.
OpenAI Codex pricing
| Plan | Price | Notes |
|---|---|---|
| Free | $0 | Limited, for exploring Codex on quick coding tasks. |
| Go | $8/month | |
| Plus | $20/month | |
| Pro | From $100/month | Much higher usage limits. |
| Business | $25/user/month | $20/user/month when billed annually. |
| API key | Pay as you go | Billed at OpenAI API rates. |
Enterprise and Edu plans are also available through OpenAI sales.
Checked on 22 Oct 2026 against the official pricing page ↗. Prices can change, so confirm before you buy.
How to get started with OpenAI Codex
- Sign in with your ChatGPT account (any plan, including Free) or prepare an OpenAI API key.
- Install the Codex CLI, IDE extension or desktop app from the official Codex page.
- Open your project and start with a question about the code to check it understands the repo.
- Give it a focused task, then review the changes before you commit them.
OpenAI Codex alternatives
Claude Code
by Anthropic
Anthropic's coding agent that works in your terminal, IDE or browser to edit code, run commands and fix bugs across a codebase.
- Not on the Claude Free plan. Included with Claude Pro ($20/month) and above, or pay as you go through the API.
- Checked 22 Oct 2026
GitHub Copilot
by GitHub
GitHub's AI pair programmer for completions, chat and coding agents inside your editor, the CLI and GitHub.
- Free plan available. Pro $10/month; Business $19/user/month.
- Checked 22 Oct 2026
Cursor
by Anysphere
An AI code editor with built-in agents, chat and tab completion that can edit and run code across your project.
- Free plan available. Paid plans from $8/month; Teams from $30/user/month.
- Checked 22 Oct 2026
OpenAI Codex FAQ
Is OpenAI Codex free?
Codex is included in ChatGPT plans, including the Free plan with limited usage. Paid plans such as Plus and Pro raise the limits.
Can I use Codex with an API key?
Yes. Instead of a ChatGPT plan, you can use Codex with an OpenAI API key and pay at API rates.
Where can I use Codex?
In a terminal through the CLI, in your editor through the IDE extension, in the desktop app and on the web through ChatGPT.