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URL to APK vs URL to AAB: which file do you need?

A URL to app build gives you two files that look interchangeable. They aren't — and using the wrong one is the commonest first-week mistake.

Updated Oct 20262 min readurltoapp.dev

Short answer

Use the APK to install the app directly — on your phone, your team's phones, or for sharing outside Google Play. Use the AAB (Android App Bundle) to publish on Google Play, which has required AABs for new apps since 2021. Play turns the AAB into optimised APKs for each device. Both come from the same URL to app build.

The short difference

APKAAB
What it isA ready-to-install Android packageA publishing format Google Play builds APKs from
Install by tapping itYesNo
Google Play (new apps)Not acceptedRequired
Other stores & direct sharingYesRarely
Download size for usersEverything for every deviceOnly what each device needs

For a URL app, size hardly matters

AABs shine for big apps with lots of images for different screen densities and code for different processors. A URL app is tiny — its content lives on your server — so the size saving is small. The real reason to use the AAB is simply that Play requires it.

Signing: the part that matters

With Play App Signing (the default for new apps), you sign the AAB with an upload key and Google re-signs the APKs it delivers with the app signing key it keeps. That has two practical effects:

  • An APK you install directly and the Play version are signed by different keys, so Android won't update one with the other. Uninstall the sideloaded copy before installing from Play.
  • For App Links, the SHA-256 fingerprint in your assetlinks.json must be the app signing key from Play Console (Setup → App signing), not your upload key — or include both.

Which to send to whom

  • Testing yourself: APK.
  • Client or team preview: APK by link or QR code, or a Play internal testing track.
  • Google Play: AAB, every release, with a higher version code each time.
  • Samsung Galaxy Store, Amazon, Huawei, your own website: APK (check each store's current rules).

FAQ

Can I convert an AAB to an APK?

Yes, with Google's bundletool you can generate APKs from an AAB, but for a URL app it's simpler to use the APK the converter already gave you.

Why won't my APK update the Play Store version?

They're signed with different keys when Play App Signing is on. Uninstall one before installing the other.

Do I get both files from one URL to app build?

Yes. Website to App returns a signed APK and an AAB from the same build.

Read next

/learn/convert-url-to-app-step-by-step/LearnConvert a URL to an app, step by stepConvert any website URL into an Android app in minutes: prepare the link, set name, icon and package, build a signed APK and AAB, then publish./learn/google-play-policy-for-url-apps/LearnGoogle Play policy for URL appsWhy Google Play rejects some website-to-app conversions (minimum functionality, webview spam, impersonation) and the checklist that gets a URL app approved./learn/url-app-deep-links/LearnDeep links & App LinksMake links to your website open straight in your URL app with Android App Links: intent filters, assetlinks.json, SHA-256 fingerprints and how to test verification./learn/update-url-app-without-rebuild/LearnUpdating without a rebuildContent, design and features on your site update a URL app instantly. Name, icon, start URL, permissions and SDKs need a new build with a higher version code./learn/what-is-url-to-app/LearnWhat is URL to App?URL to App explained: how a website link becomes an installable Android app (APK/AAB), what the app can do, what it can't, and when a URL app is the right choice./learn/how-a-url-app-works/LearnHow a URL app works insideInside a URL to app conversion: the Android activity, the WebView and its settings, cookies and storage, the user agent, the back button and how the app is signed.