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Installing Codex in VS Code ​

A setup guide for non-experts. Accurate as of September 2026. If a screen looks different, check the official guide: https://developers.openai.com/codex/ide

Using Claude Code instead? Follow "Installing Claude Code in VS Code" and skip this guide.

What You Are Setting Up ​

Codex is an AI coding assistant made by OpenAI. It runs inside VS Code as a chat panel next to your files. It can read your project, make changes, and run commands for you.

One thing to know from the start: Codex changes files in your project without asking first. It does ask before using the internet or touching anything outside your project folder. Because of this, you'll get in the habit of saving a starting point before each task, so you can always go back.

You don't need to know how to program to follow this guide.

Words You'll See ​

  • Extension: an add-on that gives VS Code new features. Codex is one.
  • Prompt: a message you send to Codex.
  • Chat: one conversation with Codex. You can start a fresh one at any time. Other guides may call this a session.
  • Permission mode: a setting that controls what Codex can do without asking.
  • Command: an instruction for your computer, usually typed in a terminal. Codex can run commands for you.
  • Command Palette: a search box at the top of VS Code for finding any command by name. Press Cmd + Shift + P on a Mac or Ctrl + Shift + P on Windows, type part of the command's name, choose it from the list, and press Enter.
  • Save point: a saved snapshot of your project (a "commit") that you can go back to.

Before You Start ​

This guide assumes:

  • VS Code is installed, up to date, and open. To update it, go to Code → Check for Updates on a Mac or Help → Check for Updates on Windows.
  • You have a ChatGPT account. Codex is included with ChatGPT plans, including the free plan, which has lower limits.

You don't need a project or a folder open to install Codex. The next guide sets up a folder for your projects.

Step 1: Install the Extension ​

  1. Open the Extensions view. Press Cmd + Shift + X on a Mac or Ctrl + Shift + X on Windows. You can also click the four-squares icon in the left-hand bar.
  2. Search for Codex.
  3. Choose Codex – OpenAI's coding agent, published by OpenAI.
  4. Click Install.

You only do this once. The extension is then available in every VS Code window and project, and each chat works on the folder that's open.

Step 2: Open Codex and Sign In ​

  1. Look for the Codex icon in the sidebar on the right side of the window, and click it. If you don't see it, open the Command Palette, type Open Codex Sidebar, and press Enter.
  2. Choose to sign in with your ChatGPT account.
  3. Your browser opens. Log in to ChatGPT and approve the connection.
  4. Go back to VS Code. You should now see a prompt box in the Codex panel.

Starting a new chat. You sometimes need a fresh chat, for example after changing a setting. Click the new chat button at the top of the Codex panel, or press Cmd + N on a Mac or Ctrl + N on Windows while the Codex panel is selected.

Step 3: Claim Your Student Credits (If Eligible) ​

OpenAI offers verified university students in the United States and Canada $100 in Codex credits. The credits let you keep using Codex after you reach your plan's usage limits.

  1. In your browser, go to https://chatgpt.com/codex/students
  2. Sign in with your ChatGPT account.
  3. Verify that you're a student, using your university email address.

The credits are added to your ChatGPT account automatically. Skip this step if it doesn't apply to you.

Step 4: Try It ​

Start with a prompt that doesn't change anything:

In plain language, what can you help me with while I build a prototype in VS Code? Keep it short.

Step 5: Understand Permissions ​

Below the prompt box is a permission mode control. It has three choices:

ModeWhat happens
Ask for approvalCodex edits files and runs routine commands in your project folder on its own. It asks before using the internet or going outside your project folder. Keep this one.
Approve for meCodex decides on its own whether to allow those requests.
Full accessCodex can change any file on your computer and use the internet without asking. Avoid this.

After each task, Codex lists the files it changed. Read the summary, and look at any file you're unsure about.

Deciding whether to allow something ​

When Codex does ask, check before you allow:

  • Read Codex's explanation. If there isn't one, ask: "Explain that in plain language first."
  • Allow it if it matches what you asked for.
  • Deny it and ask why if it would delete files, uses sudo, or changes things outside your project folder.
  • When in doubt, deny. Codex will explain or suggest another way.

Save points ​

Because Codex doesn't ask before changing your files, save a starting point before each task. Once Git is set up on your computer (that's the next guide), send this before any change:

Commit my current work with a clear message.

If a change goes wrong, you can ask Codex to go back to that save point.

Checkpoint ​

Before moving on, check that Codex is working.

  1. Start a new chat: click the new chat button at the top of the Codex panel.
  2. Send:

Say hello, and tell me in one sentence what you can help me with.

You should see: a short reply in the Codex panel. That is all this guide sets out to do: Codex installed, signed in, and answering.

If not: see Troubleshooting below.

Troubleshooting ​

The Codex icon is missing. Open the Command Palette, type Open Codex Sidebar, and press Enter. If nothing happens, open the Command Palette again and run Developer: Reload Window. Also check that the folder isn't in Restricted Mode: if VS Code asks whether you trust the authors of the folder, click Yes, I trust the authors.

The browser didn't open when I tried to sign in. Run Developer: Reload Window from the Command Palette, then try signing in again.

Windows: Codex asks to set something up first. Codex uses a protected area on Windows, called a sandbox, to run commands safely. If it asks to set this up, follow its prompts.

Codex doesn't respond. Check your internet connection, then start a new chat.

Typing codex in the terminal says "command not found". This is normal. The extension doesn't install the terminal version, and you don't need it.

Tips ​

  • Hide VS Code's built-in AI. VS Code has its own AI assistant, GitHub Copilot, whose icons sit near Codex's. If you find yourself clicking the wrong one, hide it: open VS Code settings with Cmd + , on a Mac or Ctrl + , on Windows, type @id:chat.disableAIFeatures in the search box, and check the box next to the setting that appears. This hides VS Code's own AI features only. It doesn't affect the Codex extension.
  • Check your usage. Type /status in the prompt box to see your account and usage. If you claimed student credits, your balance appears on your ChatGPT usage page.
  • Privacy. OpenAI may use your Codex chats to improve its models unless you turn this off in ChatGPT's Data controls settings.

Next ​

When this guide's checkpoint works, continue with Setting Up Git and GitHub CLI, where you make a folder for your projects, and Codex connects your computer to GitHub and brings your project into it.