Installing OpenAI Codex

OpenAI Codex is an AI coding assistant that runs directly on your computer. This guide walks you through downloading the app, installing it, and signing in for the first time.

Estimated time: 5–10 minutes

Mac

Step 1: Download and install Codex

Go to openai.com/codex and click Download for macOS
Once downloaded, open your Downloads folder and double-click the .dmg file
A new window will open showing the Codex icon and an Applications folder
Click and drag the Codex icon onto the Applications folder icon
Wait for the copy to finish, then close the window

Step 2: Open Codex for the first time

Open Finder, click Applications on the left, and find Codex
Double-click Codex to open it

Note: You may see a message saying “Codex can’t be opened because it’s from an unidentified developer.” To get past it:

Click Done to dismiss the warning

Open System Settings → Privacy & Security

Scroll down and click Open Anyway next to the Codex message

Enter your Mac password if prompted

Windows

Step 1: Install Codex from the Microsoft Store

Press the Start button (Windows logo in the bottom-left corner) and search for Microsoft Store
Open the Microsoft Store app
In the search bar at the top, type Codex and press Enter
Click on the Codex result published by OpenAI
Click Get or Install and wait for the download to complete

Step 2: Open Codex

Press the Start button and search for Codex
Click Codex to open it

Mac