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Android App Links

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Learn how to configure Android App Links to open your Expo app from a standard web URL.

To configure Android App Links for your app, you need to:

  • Add intentFilters and set autoVerify to true in your project's app config
  • Set up two-way association to verify your website and native app

Add intentFilters to the app config

Configure your app config by adding the android.intentFilters property and setting the autoVerify attribute to true. Specifying autoVerify is required for Android App Links to work correctly.

The following example shows a basic configuration that enables your app to appear in the standard Android dialog as an option for handling any links to the webapp.io domain. It also uses the regular https scheme since Android App Links are different from standard deep links.

app.json
{
  "expo": {
    "android": {
      "intentFilters": [
        {
          "action": "VIEW",
          "autoVerify": true,
          "data": [
            {
              "scheme": "https",
              "host": "*.webapp.io",
              "pathPrefix": "/records"
            }
          ],
          "category": ["BROWSABLE", "DEFAULT"]
        }
      ]
    }
  }
}

Set up two-way association

To setup two-way association between the website and Android app, you will need the following:

  • Website verification: This requires creating a assetlinks.json file inside the /.well-known directory and hosting it on the target website. This file is used to verify that the app opened from a given link is the correct app.
  • Native app verification: This requires some form of code signing that references the target website domain (URL).

Create assetlinks.json file

1

Create an assetlinks.json file for the website verification (also known as digital asset links file) at /.well-known/assetlinks.json. This file is used to verify that the app opened for a given link.

If you're using Expo Router to build your website (or any other modern React framework such as Remix, Next.js, and so on), create assetlinks.json at public/.well-known/assetlinks.json. For legacy Expo webpack projects, create the file at web/.well-known/assetlinks.json.

2

Get the value of package_name from your app config, under android.package.

3

Get the value of sha256_cert_fingerprints from your app's signing certificate. If you're using EAS Build to build your Android app, after creating a build:

  • Run eas credentials -p android command, and select the build profile to get its fingerprint value.
  • Copy the fingerprint value listed under SHA256 Fingerprint.
Alternate method to obtain the SHA256 certificate fingerprint from Google Play Console

If you're not using EAS to manage code signing, you can find the sha256_cert_fingerprints by building and submitting your app manually to the Google Play Console:

  • Inside the Google Play Console's dashboard, go to Release > Setup > App Signing.
  • Find the correct Digital Asset Links JSON snippet for your app.
  • Copy the value looks like 14:6D:E9:83... and paste it into your public/.well-known/assetlinks.json file under sha256_cert_fingerprints.

4

Add package_name and sha256_cert_fingerprints to the assetlinks.json file:

public/.well-known/assetlinks.json
[
  {
    "relation": ["delegate_permission/common.handle_all_urls"],
    "target": {
      "namespace": "android_app",
      "package_name": "com.example",
      "sha256_cert_fingerprints": [
        // Supports multiple fingerprints for different apps and keys
        "14:6D:E9:83:51:7F:66:01:84:93:4F:2F:5E:E0:8F:3A:D6:F4:CA:41:1A:CF:45:BF:8D:10:76:76:CD"
      ]
    }
  }
]
You can add multiple fingerprints to the sha256_cert_fingerprints array to support different variants of your app. For more information, see Android's documentation on how to declare website associations.

Host assetlinks.json file

Host the assetlinks.json file using a web server with your domain. This file must be served with the content-type application/json and accessible over an HTTPS connection. Verify that your browser can access this file by typing the complete URL in the address bar.

Native app verification

Install the app on an Android device to trigger the Android app verification process.

Once you have your app opened, see Handle links into your app for more information on how to handle inbound links and show the user the content they requested.

Debugging

The Expo CLI enables you to test Android App Links without deploying a website. Utilizing the --tunnel functionality, you can forward your dev server to a publicly available HTTPS URL.

1

Set the environment variable EXPO_TUNNEL_SUBDOMAIN=my-custom-domain where my-custom-domain is a unique string that you use during development. This ensures that your tunnel URL is consistent across dev server restarts.

2

Add intentFilters to your app config as described above. Replace the host value with a Ngrok URL: my-custom-domain.ngrok.io.

3

Start your dev server with the --tunnel flag:

Terminal
- npx expo start --tunnel

4

Compile the development build on your device:

Terminal
- npx expo run:android

5

Use the following adb command to start the intent activity and open the link on your app or type the custom domain link in your device's web browser.

Terminal
- adb shell am start -a android.intent.action.VIEW -c android.intent.category.BROWSABLE -d "https://my-custom-domain.ngrok.io/" <your-package-name>

Troubleshooting

Here are some common tips to help you troubleshoot when implementing Android App Links:

  • Ensure your website is served over HTTPS and with the content-type application/json
  • Verify Android app links
  • Android verification may take 20 seconds or longer to take effect, so be sure to wait until it is completed.
  • If you update your web files, rebuild the native app to trigger a server update on the vendor side (Google)