Prerequisites

This step is a one-off. Anything already installed on your machine, you can skip past.

If more than half of the commands here feel unfamiliar, glance at the “Who this guide was written for” section in Getting started first. The expected starting level for this manual is spelled out there.

Things that differ by operating system

Item	macOS	Windows	Linux
Which terminal you use	Terminal.app or iTerm2	I recommend Ubuntu running on WSL2. PowerShell is technically possible, but the guide gets longer.	Whatever shell ships with your distribution
Verified status	Verified	Install WSL2 first, then run everything inside it	Verified

If you are on Windows, finish the WSL2 install guide before coming back here. Every command in this manual assumes you are inside the Ubuntu shell on WSL2.

1) Node.js 20 or newer

On macOS and Linux: nvm

Open a terminal and run these one line at a time.

# Install nvm (Node Version Manager)
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash

# Either open a new terminal, or paste these two lines to load nvm right now
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"

# Install Node 20 and start using it
nvm install 20
nvm use 20

Verify the install

node --version    # should print v20.x.x
npm --version     # should print something like 10.x.x

If either command prints nothing at all, look at the “Node will not install” entry in 06-troubleshooting.md.

2) git

macOS

xcode-select --install

If git is already on your system the command prints a message and exits.

Linux (Ubuntu / Debian)

sudo apt update && sudo apt install -y git

Verify the install

git --version    # git version 2.x.x

Tell git who you are (one-time)

git config --global user.name "Your Name"
git config --global user.email "[email protected]"

This name and email show up as the author on any commit you make. If you want to keep this separate from your work email later, you can override it per repository — for now, fill in something reasonable.

3) Chrome and developer mode

I am assuming Chrome is already installed. The only piece you need to switch on is developer mode.

1. Type chrome://extensions into the address bar.
2. Toggle Developer mode in the top-right corner.
3. With that toggle on, you can load the extension folder or zip directly to test it.

The developer mode toggle sits in the top-right corner of the page. When it turns blue, three new buttons — including “Load unpacked” — appear in the top-left. If those buttons are not there, the toggle is still off, or the page needs a refresh.

Screenshot

Actual capture to be added later via the docs-screenshot skill. Slot: static/img/chrome-ext/beginner/prerequisites-01-dev-mode-toggle.png.

Chrome version 114 or newer is required for sidepanel to work. Type chrome://version into the address bar to check. If you are on an older version, let Chrome auto-update once.

4) Claude Code

The official install guide is the source of truth. After installing it, run claude once to log in (or register an API key if you prefer that route).

claude --version

If that prints a version number, you are ready. You can also use OpenAI Codex CLI instead of Claude Code — its entry point is AGENTS.md at the repo root and the same flow applies. If this is your first time, I would still suggest Claude Code.

5) (Optional) A code editor

If you want to look at the code as it is generated, VS Code is a comfortable choice. The AI writes everything for you, so an editor is not strictly required, but it helps when you want to see what happened.

Next

Once all five items are in place, head over to 02-clone-and-install.md.