The north star is simple: time from npm create proto@latest to a working prototype running in the iOS Simulator — under 90 seconds. You need two things installed once before that command works. Both are free. Both are macOS-only.

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Step 1 — Install Node.js

Node.js 18 or newer is the only prerequisite. Download the LTS version from nodejs.org and install it. Download Node.js → You’ll know it worked when you can open Terminal and type: 
node --version
If you see a version number, you’re done.

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Step 2 — Install Xcode

Xcode is Apple’s developer tool. Prototo uses its iOS Simulator — the iPhone preview that runs on your Mac. You never need to open Xcode itself. Just install it. Download Xcode free from the Mac App Store: Download Xcode → After installing, open Terminal and run this once: 
xcode-select --install
This installs the command line tools Xcode needs to run the Simulator.
Xcode is ~8GB. Plan for 20-40 minutes depending on your connection.

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Step 3 — Install Claude Code

Claude Code is the design tool. You’ll describe screens in plain language and it will write them into your project. There is no other prompt surface — Claude Code CLI is the only one. Install it by running: 
npm install -g @anthropic-ai/claude-code
You’ll need an Anthropic account. Sign up at claude.ai if you don’t have one.

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Step 4 — Create your first Proto project

Once the above are done: 
npm create proto@latest myapp
Proto scaffolds the project, installs dependencies silently, and opens the iOS Simulator. You’ll see the starter screen. That’s it. You’re ready.