Migrating an Android WebView App to a Trusted Web Activity

For years, rendering web content inside a native Android container meant relying on Android WebView. While WebView is highly flexible, it suffers from significant limitations: it does not share cookies or storage with the system browser, its rendering engine can lag behind modern standards, and it does not support critical Progressive Web App (PWA) features out of the box. Migrating your hybrid wrapper or legacy app to a Trusted Web Activity (TWA) resolves these issues by running your web application directly inside the user's default browser engine, such as Chrome.

Why Migrate from WebView to Trusted Web Activity?

The primary drawback of a legacy WebView app is storage isolation. When a user logs into your website via their system browser, they must log in again inside your WebView app because the two runtimes do not share a cookie store. A Trusted Web Activity uses a shared cookie jar with the host system browser. This means that if a user is already authenticated on your website, they are instantly logged into your installed TWA app.

Furthermore, TWAs run on the latest system-installed browser engine. This guarantees immediate support for cutting-edge web APIs, hardware acceleration, and superior performance without waiting for Android system updates to refresh the underlying WebView rendering engine.

Step 1: Updating Your Android Project Dependencies

To begin the migration, you must update your Android project to import the official Android Browser Helper library. This library simplifies launching and managing Trusted Web Activities. Open your app-level build.gradle file and add the required dependency to your dependencies block.

implementation 'com.google.android.play:app-update:2.1.0'

implementation 'androidx.browser:browser:1.8.0'

You must also ensure that your project compileSdkVersion and targetSdkVersion are configured to at least API level 33 to support modern Android features and policy requirements.

Step 2: Restructuring the Manifest

In a standard WebView application, you load content by instantiating a custom WebView client inside a Java or Kotlin activity. With a TWA, you replace this logic by registering the pre-configured LauncherActivity provided by the Android Browser Helper library inside your AndroidManifest.xml.

First, remove your old WebView activity declaration from the manifest. Then, add the TWA launcher activity with the appropriate intent filters. Below is the structure required to direct the launcher to load your web origin:

<activity android:name="com.google.android.keytool.LauncherActivity"><intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

<meta-data android:name="android.support.customtabs.trusted.DEFAULT_URL" android:value="https://yourdomain.com" />

</activity>

You must also define your app's package identity and configure the system color metadata inside the application tag to align the splash screen and status bar experience with your brand identity.

Step 3: Implementing Digital Asset Links

Unlike a WebView app, which can display any webpage inside an arbitrary frame, a Trusted Web Activity requires explicit mathematical proof that you own the web domain you are loading. This proof is established via Digital Asset Links. If you fail to configure this step, your TWA will display the browser's address bar at the top of the interface, breaking the native look and feel.

To configure domain verification, follow these steps:

• Generate your SHA-256 app signing certificate fingerprint from your Google Play Console or using the local Java keytool command.
• Create an assetlinks.json file containing your package name and SHA-256 fingerprint.
• Upload the assetlinks.json file to your web server under the path: /.well-known/assetlinks.json.
• Ensure the file is served with the correct Content-Type header of application/json and returns an HTTP status code of 200.

Step 4: Preserving User Session States During Migration

Because legacy WebViews isolate storage from the standard browser profile, migrating your container to a TWA means your active users will initially lose their logged-in states upon installing the new version. Because the TWA looks at the system browser cookie jar instead of the old private WebView database, users will appear logged out on their first launch.

To mitigate this friction, you can implement a one-time session transfer protocol during migration:

• Before releasing the TWA update, update your WebView container to export the user's authentication token from the WebView cookie storage.
• Save this token securely to the Android SharedPreferences system.
• On the first launch of the updated TWA, append a secure, one-time verification token as a query parameter to your launch URL.
• Your web server can read this token, validate it, establish the session cookie inside the system Chrome browser, and immediately redirect to the clean home URL.

By executing this sequence, you preserve existing user sessions and guarantee a seamless transition from your old WebView wrapper to a modern, lightweight Trusted Web Activity container.