AI coding agent
Codex
Codex is OpenAI's coding agent. It reads and edits code, runs commands and reviews pull requests, and it runs in the ChatGPT desktop app, in an open-source CLI, in IDE extensions, in the cloud and on iOS. Codex usage is included in ChatGPT plans from Free to Enterprise, or billed at API rates with an API key.
Last reviewed 28 Oct 2026 · by OpenAI
Facts at a glance
| Developer | OpenAI |
|---|---|
| Type | Agentic coding tool, CLI and desktop app |
| Surfaces | ChatGPT desktop app, Codex CLI, IDE extension, Codex Cloud on the web, iOS source |
| Plans | Included in ChatGPT Free, Go, Plus, Pro, Business, Edu and Enterprise; API key use billed at API prices source |
| Install (CLI) | npm install -g @openai/codex source |
| License | Apache-2.0 (Codex CLI repository) |
| Latest CLI in this review | 0.165.0, released 27 October 2026 source |
What Codex is used for
OpenAI documents Codex for writing features, fixing bugs, running long tasks in cloud environments, automatic code review on GitHub and work through integrations such as Slack and Linear. Codex and ChatGPT Work share usage limits and credits. OpenAI ships CLI releases several times a week and lists them, with desktop app and model changes, in the ChatGPT and Codex changelog. The timeline below lists every story on this site that names Codex.
Questions people ask
- Is Codex free?
- OpenAI says Codex is included in every ChatGPT plan, including Free at $0 per month, with limits that depend on the plan. Use with an API key is billed at API token prices.
- Is the Codex CLI open source?
- Yes. The CLI is developed in the public openai/codex repository on GitHub under the Apache-2.0 license.