How to use Codex in 2026: the app, the CLI, your editor and the cloud

To use Codex, OpenAI's coding agent, sign in with a ChatGPT account and pick a surface: the Codex mode in the ChatGPT desktop app, the Codex command-line tool (install it with curl -fsSL https://chatgpt.com/codex/install.sh | sh on Mac or Linux, then run codex), the extension for VS Code or Cursor, Codex Cloud for tasks that run on OpenAI's machines, or the ChatGPT phone app. Every ChatGPT plan includes some Codex: Free and Go get the small GPT-6 Luna model in the desktop app, and Plus at $20 unlocks the CLI, the editor extension, the cloud and GPT-6.1 Sol.

Key takeaways

• The desktop app: Codex joined the ChatGPT desktop app on July 9, 2026; switch to Codex at the top.
• The CLI: one-line installers for Mac, Linux and Windows, or npm install -g @openai/codex. Sign in with codex login.
• Your editor: the Codex extension runs in VS Code, Cursor and Windsurf; JetBrains IDEs run Codex inside JetBrains AI.
• Instructions: put project instructions in AGENTS.md; /init writes a starter file.
• With Claude Code: OpenAI's official plugin adds /codex:review and other Codex commands inside Claude Code.

How do you install the Codex CLI?

From OpenAI's docs (OpenAI):

• Mac or Linux: curl -fsSL https://chatgpt.com/codex/install.sh | sh
• Windows, in PowerShell: powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"
• npm: npm install -g @openai/codex. Homebrew works too.

Run the same command again, or codex update, to update. Codex runs natively on Windows with its own sandbox; WSL2 is optional. The CLI is open source under Apache 2.0 (GitHub).

How do you sign in?

• With ChatGPT: codex login opens a browser. On a machine without one, codex login --device-auth.
• With an API key: printenv OPENAI_API_KEY | codex login --with-api-key, billed at API rates and without cloud features.
• codex login status shows which you're using (OpenAI).

Your first session in the terminal

1. Open your project folder and run codex.
2. Run /init to create an AGENTS.md with project instructions.
3. Describe the change you want. Codex reads files, runs commands and edits code.
4. Use /plan to agree on an approach first, /review to have it review changes, and /diff to see them.
5. Come back later with codex resume, or codex resume --last for the latest session.

Permissions: by default Codex can edit files in your project but has no network, and asks before going further. Choose read-only, workspace-write or danger-full-access with --sandbox, and how often it asks with -a. The --yolo flag skips both approvals and the sandbox; use it only in a throwaway environment (OpenAI).

How do you use Codex in VS Code or Cursor?

Install the Codex extension from the marketplace (openai.chatgpt), then open it from its icon or the command "Codex: Open Codex Sidebar" (OpenAI). It works in VS Code, VS Code Insiders, Cursor and Windsurf. In JetBrains IDEs, open AI Chat and choose Codex.

How do you use Codex in ChatGPT?

In the ChatGPT desktop app for Mac and Windows, choose Codex at the top and start a new chat in a project folder. The app adds worktrees for parallel chats, scheduled tasks, a built-in browser and the option to move a chat to the cloud. It's also where Free and Go users get Codex.

How do you run Codex in the cloud?

Codex Cloud runs tasks on OpenAI's machines against a GitHub repository. Set up an environment (connect GitHub, choose the repository and publish the environment), then start tasks from ChatGPT on the web or desktop (OpenAI). From the terminal, codex cloud lists and starts cloud tasks and codex apply brings a result's changes into your local copy. Cloud tasks need a ChatGPT sign-in and a paid plan.

Can you use Codex on your phone?

Yes, in the ChatGPT iPhone app: it runs Codex tasks in the cloud, or on a Mac or PC you connect from the desktop app's settings (OpenAI).

How do you use Codex with Claude Code?

• Inside Claude Code: OpenAI's official plugin, openai/codex-plugin-cc, adds Codex commands to Claude Code. Install it with /plugin marketplace add openai/codex-plugin-cc and /plugin install codex@openai-codex, then run /codex:setup (GitHub). /codex:review has Codex review your changes, /codex:rescue hands a task to Codex, and /codex:transfer turns the session into a Codex thread. It needs the Codex CLI and counts against your Codex limits.
• The old MCP route is gone: OpenAI removed the codex mcp-server command on September 5, 2026.
• The other direction: /import in Codex brings in Claude Code's setup, memories, MCP servers and recent chats.

Using two labs' agents on one codebase is covered in Cross-model code review and Claude Code vs Codex; the Claude Code side is in How to use Claude Code.

Which plan do you need?

• Free and Go ($8): GPT-6 Luna in the desktop app.
• Plus ($20): the CLI, editor, cloud and phone, GitHub reviews, and GPT-6.1 Sol.
• Pro ($100, $200 or $500): much higher limits and no five-hour window (ChatGPT Plus vs Pro, Codex pricing).
• Business: $20 a user billed annually, $25 monthly (Codex for teams).

More on what's free in Is Codex free?.

Using Codex as a team

Codex sessions belong to the person who started them. Poly (usepoly.co) runs Codex and Claude Code in a shared browser room where a team works with one agent: everyone sees each step live, and any member can approve a change before it happens. Free to start. What is Poly?