Module 0.2: Get the Codex App
Reference Guide
- Time to Complete: 5 minutes
- Prerequisites: Mac or Windows + a ChatGPT account
📖 Overview
You’ll download the Codex app and sign in with your ChatGPT account. That’s it — it installs like any other app, and once you’re signed in you’re ready to open the course.
Key takeaway: Download the app from openai.com/codex, open it, choose Sign in with ChatGPT.
Step 1: Download the App
⬇️ Get Codex at openai.com/codex →
Click the download button for your platform — Codex is available for Mac and Windows.
Step 2: Install and Open It
It installs like any other app:
- Mac: open the downloaded file and drag Codex into your Applications folder, then launch it.
- Windows: run the installer and follow the prompts, then launch Codex.
Step 3: Sign In
- When Codex opens, choose “Sign in with ChatGPT” (recommended) and complete the login in your browser.
- That’s it — Codex now uses your ChatGPT subscription.
Prefer pay-as-you-go? You can sign in with an OpenAI API key instead (billed per use). For this course, signing in with ChatGPT is simpler.
Step 4: Pick a Plan
Codex is included across ChatGPT plans. You can start free; most PMs are comfortable on Plus.
| Plan | Price | Good for |
|---|---|---|
| Free | $0 | Trying Codex on light tasks |
| Go | $8/mo | Occasional, lightweight use |
| Plus | $20/mo | Recommended — daily PM work |
| Pro | $100+/mo | Heavy use, much higher limits |
Usage limits and model availability change often — check the current pricing page for the latest. If you hit a limit, Codex lets you top up with credits without upgrading.
A Note on Permissions
The first time Codex makes changes, it asks for permission. By default it works in Auto mode — it reads, edits, and runs tasks inside your current project folder, and asks before touching anything outside it. That’s exactly right for this course.
Codex always shows you what it did, so nothing happens silently. You can review every change.
🐛 Troubleshooting
Sign-in browser window doesn’t open
- Quit and reopen the Codex app, then try signing in again.
Not sure which plan you’re on
- Check chatgpt.com → Settings → Subscription. Any plan works for starting the course.
The app won’t open (Mac)
- If macOS blocks it, go to System Settings → Privacy & Security and click Open Anyway.
🚀 What’s Next?
Module 0.2 complete — the Codex app is installed and you’re signed in.
Next: Module 0.3 — Opening the Course. You’ll download the course files, open them in the Codex app, and run your first lesson.
Go to Module 0.3: Opening the Course →
📚 Resources
- OpenAI Codex — download page
- Codex app docs — official guide to the app
- Codex pricing — current plans and limits