How to build an app with Claude Code: from idea to working app

Why Claude Code plus Expo changes who can build an app

For years, building a mobile app meant either learning Swift or Kotlin for months or paying a developer five to ten thousand dollars, sight unseen. Claude Code plus Expo removes both. You describe what you want in plain English, Claude Code writes the React Native code, and Expo runs it as a real app on your phone. The person who could never build an app - no coding background, no developer budget - can now ship one. That shift is the whole reason a non-technical founder can put a working app in their hand in a week.

Set up the build machine first

Before you build anything, set up the Claude Code plus Expo build machine: Claude Code as the tool that writes the code, an Expo project as the app, and the Expo Go app on your phone to run it live. Once this is wired, you can type a plain-English request and see the result on your phone in seconds. No Mac is required because EAS builds in the cloud. Getting this setup right once is what turns every later step from a technical hurdle into a plain-English conversation with Claude Code.

• Claude Code - the tool that writes the native app code from your plain English
• Expo - the framework that runs your app as a real app on your phone
• Expo Go - preview your app live on your phone as Claude Code builds it
• EAS Build and Submit - cloud builds for both stores, no Mac required
• RevenueCat and Supabase - the paywall and the backend, wired in when you need them

Validate before you write a single screen

The biggest build mistake is building before validating. Claude Code makes building so fast that it is tempting to skip straight to code, but a beautifully built app nobody wanted is still a failure. Confirm the problem is real, read the reviews of existing apps for the gap, and write a one-page plan of the core feature first. Validation is what makes sure the app Claude Code builds is one people actually download. A separate guide in this hub covers how to validate an app idea in detail.

Mockup the screens with the AI design method

Before Claude Code writes a line, mockup your screens so Claude has a blueprint instead of a guess. The AI design method taught in the club has you generate a visual mockup of each screen first, so you can see the layout and flow before any code exists. Handing Claude Code a clear picture of what each screen should look like produces a far better result than describing it vaguely. Design first, build second - Claude builds from a blueprint, not a guess, and that is the difference between a clean app and a messy one.

Build feature by feature, not all at once

The fastest way to a working app is to build it one feature at a time, testing each on your real phone before moving on. Start with the core screen that delivers the value, get it working, then add the next piece - navigation, data, the account flow. Building in small, tested steps means every problem is easy to spot and fix, because you know exactly what just changed. The club's 69 copy-paste build prompts give you one prompt per build step, so you paste into Claude Code and the app writes itself from first screen to submission.

Wire the paywall with RevenueCat

An app that can take money needs a paywall, and RevenueCat is the tool that manages subscriptions across both stores. Wire it in once the core app works: the onboarding flow into a free trial into the subscription, tested before you submit. RevenueCat handles the store-specific plumbing so you do not have to learn each store's purchase API. Get the paywall working and tested on a real device early, because a broken purchase flow is a common Apple rejection. A separate guide in this hub covers how to price the subscription itself.

Add a backend only when the app needs one

Not every app needs a server. A habit tracker or a utility can store everything on the device and never touch a backend. An app with user accounts, sync, or shared data needs one, and Supabase provides authentication and a database with row-level security so each user only sees their own data. Add the backend only when the app genuinely needs it - a simpler app ships faster. When you do add one, wiring it correctly, with no leaked keys and a locked-down database, is part of shipping safely before you go live.

Get it store-ready and ship

Once the app works on your phone, the paywall is tested, and the backend if any is secure, it is time to get store-ready: screenshots, ASO keywords, privacy and compliance fields, and the security pass that catches leaked keys or an open database before you go live. Then EAS Build and Submit push the app to both stores from one pipeline. Building with Claude Code gets you a working app fast; the club's stages carry that app all the way from your phone to live on both stores, with the Rejection-Fix Vault as your safety net.