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Live Preview

The preview gives you two views of your app — a web preview in the browser for quick checks, and the app on your own phone from the QR code.

Two Ways to Preview​

Web preview​

The preview panel renders your app inside a phone frame, right in the browser. It's the quickest way to glance at layout and styling while you iterate.

It's an approximation, so a few things differ from a real device:

  • Native‑only features — camera, haptics, native gestures — aren't available here.
  • Some animations and platform‑specific behaviors render differently than on a phone.
  • Fonts and spacing can be slightly off.
tip

Use the web preview for layout and styling checks. In a phone's browser you see the web version of the app; for accurate fonts, native features, and true performance, run it in Expo Go on Android or install a build from the ZIP.

On your phone​

Click Open on phone in the top bar. Scan the QR with your phone's camera, then tap Open the app; the app opens in your phone's browser, on iPhone and Android alike, at real phone size and with real touch. That is the web version of the app. On Android you can also run it inside Expo Go; that is the same React Native app your users would get.

Connect Your Phone​

  1. Click Open on phone in the top bar.
  2. Scan the QR with your phone's camera, then tap Open the app. The app opens in your phone's browser.
  3. Android only: tap Open in Expo Go instead to run it in Expo Go. That needs the Expo Go build for SDK 54 from Expo's download page; the Google Play version cannot open an AppX project.

On iPhone, no Expo Go build opens an AppX project, so the browser preview is the phone view there.

The first load downloads the JavaScript bundle, so it takes longer than the ones after it.

After an Edit​

After an edit, AppX restarts the app's preview. Reload the page in your phone's browser (in Expo Go on Android: shake → Reload) to see the change; it opens at the first screen.

When Your App Is Asleep​

Each project runs in its own live app environment. An idle app goes to sleep to save resources and wakes on its own the next time you open the project or scan the QR code. Nothing is lost while it sleeps. See How Your App Runs.

Share a Preview​

Share gives a link that opens the running app in a browser. For the phone version, send them the QR from Open on phone; it opens in their phone's browser, and on Android in Expo Go too.

Troubleshooting​

QR code won't scan

  • Increase your screen brightness.
  • Scan with your phone's camera.

The app won't load

  • If the app was asleep, wait for it to wake, then try again.
  • Scan the QR code again.

Changes aren't showing

  • Reload the page in your phone's browser. In Expo Go on Android, shake the phone and tap Reload.

Crashes on the phone but looks fine in web preview

  • Usually a native feature behaving differently on device.
  • Describe what happened — "the app crashes when I tap the photo button" — and the AI will work on it.
Device Testing

The phone preview, Expo Go on Android, and iOS vs Android debugging.

How Your App Runs

How your app sleeps, wakes, and keeps your files safe.