OpenAI Codex tutorial for beginners

A complete guide to getting started with OpenAI Codex on your Mac. Learn how to set up, configure, and build your first project with the tool that pioneered AI coding.

OpenAI Codex is the AI system that pioneered the entire AI coding movement. It powers GitHub Copilot and is the technology that first showed the world what AI-assisted programming could look like.

Today, you can use Codex directly through OpenAI’s CLI tool to build complete applications by describing what you want. This tutorial will show you how to get started from scratch.

What you’ll need

  • A Mac running macOS 14 (Sonoma) or later
  • An OpenAI account with API access
  • A payment method on file (pay-per-use pricing)
  • About 15 minutes of your time

Pricing note: Codex uses OpenAI's API with pay-per-use pricing. For typical learning and experimentation, expect to spend a few dollars per month. It's very affordable for personal projects.

Step 1: Install Codex

The traditional installation requires setting up Node.js, configuring environment variables, and managing API keys. That can be intimidating if you’re new to development.

The simpler approach is to use Vibestackr—a free Mac app that handles the entire setup.

Using Vibestackr (recommended)

Download Vibestackr, open it, select "Codex" from the list, and click Install. Vibestackr installs dependencies and guides you through API key configuration.

During setup, you’ll need to enter your OpenAI API key. Vibestackr will show you exactly how to find it in your OpenAI dashboard.

Step 2: Open Terminal

After installation, you’ll use Terminal to interact with Codex:

  1. Press Cmd + Space to open Spotlight
  2. Type “Terminal” and press Enter

Step 3: Start Codex

In Terminal, type:

codex

Press Enter. Codex will initialize and you’ll see a prompt ready for your instructions.

Step 4: Build your first project

Let’s create something useful: a markdown note-taking app. Type this prompt:

Create a note-taking web app with the following features:
- Write notes in markdown
- See a live preview of the formatted markdown
- Save notes to local storage
- List all saved notes with the ability to edit or delete them
- Clean, minimal interface with a dark theme

Press Enter and watch Codex generate a complete application. It will create:

  1. The HTML structure
  2. CSS styling for the dark theme
  3. JavaScript for markdown parsing and local storage
  4. The note management functionality

Step 5: View and test

Once Codex finishes, ask it to open your creation:

Open the note app in my browser

Try it out. Create a note with some markdown (headings, bold text, lists), see the live preview, and save it.

Step 6: Add features

The real power of vibe coding is iteration. Want to improve your app? Just describe what you want:

Add syntax highlighting for code blocks in the markdown preview.

Or:

Add the ability to organize notes into folders.

Or:

Add a search bar to find notes by title or content.

Each feature gets added in seconds. You’re building real software without writing code.

Why choose Codex?

The original

Codex pioneered AI coding. OpenAI has been refining this technology longer than anyone else, and it shows in the quality of output.

Flexible pricing

Pay-per-use means you only pay for what you use. If you’re experimenting casually, it’s very affordable. Heavy users can still predict costs based on their usage patterns.

OpenAI ecosystem

Codex integrates with OpenAI’s broader AI tools. If you’re already using ChatGPT or other OpenAI services, Codex fits naturally into your workflow.

Proven reliability

Codex powers GitHub Copilot, which is used by millions of developers daily. This battle-tested technology works.

Tips for better results

Structure your prompts

Break down complex requests into clear requirements. Use bullet points or numbered lists. Codex responds well to organized prompts.

Specify technologies

If you have preferences (“use React” or “vanilla JavaScript only”), state them upfront. Codex will follow your technical requirements.

Ask for best practices

Add phrases like “following best practices” or “with proper error handling” to get more robust code.

Review the output

While Codex generates working code, it’s good practice to understand what it creates. Ask it to explain any part you don’t understand.

Project ideas

Ready to practice? Try these projects:

  • Password generator — “Create a password generator with length and complexity options”
  • Countdown timer — “Build a countdown app for events with multiple timers”
  • Bookmark manager — “Create an app to save and organize bookmarks with tags”
  • Unit converter — “Build a converter for length, weight, and temperature”
  • Color palette generator — “Create a tool that generates harmonious color palettes”

Ready to start?

Download Vibestackr and install Codex in minutes. No coding experience required.

Download Vibestackr

Comparing AI coding tools

Codex is one of several options. Here’s how it compares:

  • Codex — Pay-per-use pricing, proven reliability, OpenAI ecosystem integration
  • Claude Code — Fixed monthly subscription, excellent context understanding, great for complex projects
  • Gemini CLI — Generous free tier, fast generation, Google integration

With Vibestackr, you can install all three and discover which works best for your style. Many developers use different tools for different tasks.

Getting help

If you run into issues, ask Codex:

  • “Debug this code for me”
  • “Why am I getting this error?”
  • “How can I make this more efficient?”

Codex can analyze, explain, and fix code just as well as it generates it.

Happy vibe coding!