How to Install Codex on MacBook Air Using Command Line and App: Complete Tutorial

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Posted on | by rajeshkumar

Codex is OpenAI’s AI coding agent that helps developers understand code, modify projects, review changes, debug issues, and work inside development environments. On a MacBook Air, you can use Codex in two main ways:

  1. Codex CLI — command-line tool used inside Terminal.
  2. Codex App — desktop app for macOS with a visual interface.

OpenAI’s official Codex documentation says the CLI supports macOS and can be installed with npm or Homebrew. The Codex app is available for macOS and Windows, with a separate macOS Apple Silicon build for modern Macs like MacBook Air M-series devices. (OpenAI Developers)

1. System Requirement for MacBook Air

Your MacBook Air with Apple Silicon chip, 16GB unified memory, and 512GB SSD is suitable for Codex.

Recommended setup:

macOS: Latest available version
Chip: Apple Silicon M1/M2/M3/M4/M5
RAM: 8GB minimum, 16GB recommended
Disk: At least a few GB free
Tools: Terminal, Git, Homebrew, Node.js/npm

Before installing Codex, open Terminal.

You can find Terminal here:

Applications → Utilities → Terminal

Or press:

Command + Space → type Terminal → Enter

Part 1: Install Codex Using Command Line

2. Check Your Mac Architecture

Run:

uname -m

If you see:

arm64

That means your MacBook Air is Apple Silicon. This is expected for M-series MacBooks.

3. Install Homebrew

Homebrew is a package manager for macOS. It helps install developer tools easily.

Check whether Homebrew is already installed:

brew --version

If you see a version number, Homebrew is already installed.

If you see:

zsh: command not found: brew

install Homebrew using:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

After installation, add Homebrew to your shell path:

echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

Verify again:

brew --version

Expected output:

Homebrew 4.x.x

4. Install Git

Codex works best inside Git projects because you can review and revert code changes safely.

Install Git:

brew install git

Verify:

git --version

Example output:

git version 2.x.x

5. Install Node.js and npm

Codex CLI can be installed using npm. npm comes with Node.js.

Install Node.js:

brew install node

Verify:

node -v
npm -v

Example output:

v24.x.x
11.x.x

If both commands show versions, Node.js and npm are ready.

6. Install Codex CLI Using npm

OpenAI’s official CLI install command is: (OpenAI Developers)

npm i -g @openai/codex

After installation, check Codex:

codex --version

Then start Codex:

codex

The first time you run it, Codex will ask you to sign in using your ChatGPT account or an API key. (OpenAI Developers)

7. Alternative: Install Codex CLI Using Homebrew

OpenAI also lists Homebrew as an official install option for Codex CLI. (OpenAI Developers)

Run:

brew install codex

Then start:

codex

Use either npm or Homebrew. Do not worry if you installed using npm already. For most developers, npm installation is simple and widely used.

8. Use Codex Inside a Project

Create a test project:

mkdir ~/codex-demo
cd ~/codex-demo
git init

Create a simple file:

cat > app.py <<'EOF'
def add(a, b):
    return a + b

print(add(2, 3))
EOF

Commit your starting code:

git add .
git commit -m "Initial project before Codex"

Now start Codex:

codex

Try this prompt inside Codex:

Explain this project and suggest improvements. Do not edit files yet.

Another useful prompt:

Add basic error handling and comments to app.py. Show me the changes before finalizing.

After Codex makes changes, check:

git diff

If changes look good:

git add .
git commit -m "Update code using Codex"

If you want to discard changes:

git restore .

Part 2: Install Codex App on MacBook Air

9. Download Codex App for macOS

OpenAI provides a Codex desktop app for macOS. The Codex app documentation says it is available on macOS and Windows, and for Mac you should choose the Apple Silicon build unless you are using an Intel-based Mac. (OpenAI Developers)

Go to the official Codex page from your Mac desktop browser:

https://openai.com/codex/

or:

https://developers.openai.com/codex/app

Choose:

Download for macOS — Apple Silicon

For your MacBook Air M-series, use Apple Silicon, not Intel.

10. Install the Codex App

After downloading:

  1. Open the downloaded .dmg file.
  2. Drag Codex into the Applications folder.
  3. Open Applications.
  4. Launch Codex.
  5. Sign in with your ChatGPT account or API key.

OpenAI’s getting-started page says the Codex app welcome screen allows users to continue with ChatGPT or enter an API key. (OpenAI)

11. macOS Security Warning Fix

Sometimes macOS may show:

"Codex" cannot be opened because Apple cannot check it for malicious software.

To allow it:

System Settings → Privacy & Security → Open Anyway

Then open Codex again.

12. How to Use Codex App

After opening Codex app:

  1. Sign in.
  2. Open or connect a project folder.
  3. Ask Codex to inspect, modify, or review code.
  4. Review the generated diff.
  5. Accept or reject changes.

Useful prompts:

Review this project and explain the folder structure.

Find security issues in this Laravel application.

Create a README file for this project.

Refactor this code but keep the existing behavior unchanged.

The Codex app is designed as a visual command center for managing coding agents, reviewing diffs, and working on longer coding tasks. (OpenAI)

Part 3: Optional — Use Codex with VS Code

If you use VS Code, you can use Codex inside your editor. OpenAI says the Codex VS Code extension is compatible with VS Code and many VS Code forks, and for other IDEs you can run Codex CLI inside the IDE terminal. (OpenAI Help Center)

Install VS Code:

brew install --cask visual-studio-code

Open your project:

cd ~/codex-demo
code .

Then you can run Codex inside VS Code terminal:

codex

Part 4: Common Errors and Fixes

Error 1: npm: command not found

Reason: Node.js is not installed.

Fix:

brew install node

Verify:

node -v
npm -v

Then install Codex:

npm i -g @openai/codex

Error 2: brew: command not found

Reason: Homebrew is not installed or PATH is not configured.

Fix:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Then:

echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

Error 3: codex: command not found

Reason: Codex installed, but global npm path is not available.

Check npm global path:

npm bin -g

Check where Codex is installed:

which codex

Try reinstalling:

npm uninstall -g @openai/codex
npm i -g @openai/codex

Restart Terminal and run:

codex

Error 4: Permission error during npm install

Avoid using sudo unless absolutely necessary.

Try:

mkdir ~/.npm-global
npm config set prefix '~/.npm-global'
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.zprofile
source ~/.zprofile
npm i -g @openai/codex

Then:

codex

Error 5: Bubblewrap warning

You may see something like:

Codex could not find bubblewrap on PATH.

On macOS, this is usually not something you need to fix manually. Bubblewrap is mainly a Linux sandboxing tool. If Codex continues running, you can ignore it.

Part 5: Recommended Safe Workflow

Because Codex can edit your files, always use Git.

Before using Codex:

git status
git add .
git commit -m "Before Codex changes"

Run Codex:

codex

After Codex finishes:

git diff

If good:

git add .
git commit -m "Codex changes"

If bad:

git restore .

OpenAI’s quickstart also recommends using Git checkpoints because Codex can modify your codebase. (OpenAI Developers)

Part 6: Best Prompts for Beginners

Use clear instructions.

Good examples:

Explain this codebase like I am a beginner.

Find bugs but do not change any files.

Create a plan before editing code.

Make the smallest possible change to fix this issue.

Update this Laravel controller but keep all existing logic.

Review the security of this API route.

Write tests for this function.

Show me the diff before I accept the changes.

Final Recommended Installation Commands

For most MacBook Air users, this is the clean full setup:

# Install Homebrew
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

# Add Homebrew to PATH for Apple Silicon Mac
echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

# Install Git and Node.js
brew install git node

# Install Codex CLI
npm i -g @openai/codex

# Verify
node -v
npm -v
git --version
codex --version

# Start Codex
codex

For the app version:

Download Codex App → choose macOS Apple Silicon → install → open → sign in → open project → start coding

Conclusion

On a MacBook Air, Codex can be installed in two ways. The Codex CLI is best for developers who like Terminal and want to work directly inside project folders. The Codex App is best for users who prefer a visual interface, project overview, diffs, and agent-based workflows.

For the best setup, install both:

Codex CLI + Codex App + Git + VS Code

This gives you a complete AI coding environment on your MacBook Air.

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