bundletool

bundletool is the underlying tool that Android Studio, the Android Gradle plugin, and Google Play use to build an Android App Bundle. bundletool can convert an app bundle into the various APKs that are deployed to devices.

Android SDK Bundles (ASBs) and their APKs are built with bundletool. It is also available as a command-line tool, so you can build app bundles and SDK bundles yourself and re-create Google Play's server-side build of your app's APKs or your runtime-enabled SDK's APKs.

Download bundletool

If you haven't already, download bundletool from the GitHub repository.

Build and test an app bundle

You can use Android Studio or the bundletool command-line tool to build your Android App Bundle and then test generating APKs from this app bundle.

Build an app bundle

Use Android Studio and the Android Gradle plugin to build and sign an Android App Bundle. However, if using the IDE is not an option—for example, because you are using a continuous build server—you can also build your app bundle from the command line and sign it using jarsigner.

For more information about building app bundles with bundletool, see Build an app bundle using bundletool.

Generate a set of APKs from your app bundle

After you build your Android App Bundle, test how Google Play uses it to generate APKs and how those APKs behave when deployed to a device.

There are two ways you can test your app bundle:

This section explains how to use bundletool to test your app bundle locally.

When bundletool generates APKs from your app bundle, it includes the generated APKs in a container called an APK set archive, which uses the .apks file extension. To generate an APK set for all device configurations your app supports from your app bundle, use the bundletool build-apks command, as shown:

bundletool build-apks --bundle=/MyApp/my_app.aab --output=/MyApp/my_app.apks

If you want to deploy the APKs to a device, you also need to include your app's signing information, as shown in the following command. If you don't specify signing information, bundletool attempts to sign your APKs with a debug key for you.

bundletool build-apks --bundle=/MyApp/my_app.aab --output=/MyApp/my_app.apks
--ks=/MyApp/keystore.jks
--ks-pass=file:/MyApp/keystore.pwd
--ks-key-alias=MyKeyAlias
--key-pass=file:/MyApp/key.pwd

The following table describes the various flags and options you can set when using the bundletool build-apks command in greater detail:

Table 1. Options for the bundletool build-apks command

Flag Description
--bundle=path (Required) Specifies the path to the app bundle you built using Android Studio. To learn more, read Build your project.
--output=path (Required) Specifies the name of the output .apks file, which contains all the APK artifacts for your app. To test the artifacts in this file on a device, follow the steps in the section about how to deploy APKs to a connected device.
--overwrite Overwrites any existing output file with the path you specify using the --output option. If you don't include this flag and the output file already exists, you get a build error.
--aapt2=path Specifies a custom path to AAPT2. By default, bundletool includes its own version of AAPT2.
--ks=path (Optional) Specifies the path to the deployment keystore used to sign the APKs. If you don't include this flag, bundletool attempts to sign your APKs with a debug signing key.
--ks-pass=pass:password
or
--ks-pass=file:/path/to/file		 Specifies your keystore password. If you specify a password in plain text, qualify it with pass:. If you pass the path to a file that contains the password, qualify it with file:. If you specify a keystore using the --ks flag without specifying --ks-pass, bundletool prompts you for a password from the command line.
--ks-key-alias=alias Specifies the alias of the signing key you want to use.
--key-pass=pass:password
or
--key-pass=file:/path/to/file		 Specifies the password for the signing key. If you specify a password in plain text, qualify it with pass:. If you pass the path to a file that contains the password, qualify it with file:.

If this password is identical to the one for the keystore itself, you can omit this flag.
--connected-device Instructs bundletool to build APKs that target the configuration of a connected device. If you don't include this flag, bundletool generates APKs for all device configurations your app supports.
--device-id=serial-number If you have more than one connected device, use this flag to specify the serial ID of the device to which you want to deploy your app.
--device-spec=spec_json Provides a path to a .json file that specifies the device configuration you want to target. To learn more, go to the section about how to Generate and use device specification JSON files.
--mode=universal Sets the mode to universal. Use this option if you want bundletool to build a single APK that includes all of your app's code and resources, so that the APK is compatible with all device configurations your app supports.

Note: bundletool includes only feature modules that specify <dist:fusing dist:include="true"/> in their manifest in a universal APK. To learn more, read about the feature module manifest.

Keep in mind, these APKs are larger than those optimized for a particular device configuration. However, they're easier to share with internal testers who, for example, want to test your app on multiple device configurations.

--local-testing Enables your app bundle for local testing. Local testing allows for quick, iterative testing cycles without the need to upload to Google Play servers.

For an example of how to test module installation using the --local-testing flag, see Locally test module installs.

Deploy APKs to a connected device

After you generate a set of APKs, bundletool can deploy the right combination of APKs from that set to a connected device.

For example, if you have a connected device running Android 5.0 (API level 21) or higher, bundletool pushes the base APK, feature module APKs, and configuration APKs required to run your app on that device. Alternatively, if your connected device is running Android 4.4 (API level 20) or lower, bundletool searches for a compatible multi-APK to deploy to your device.

To deploy your app from an APK set, use the install-apks command and specify the path of the APK set using the --apks=/path/to/apks flag, as shown in the following command. If you have multiple devices connected, specify a target device by adding the --device-id=serial-id flag.

bundletool install-apks --apks=/MyApp/my_app.apks

Generate a device-specific set of APKs

If you don't want to build a set of APKs for all device configurations your app supports, you can build APKs that target only the configuration of a connected device using the --connected-device option, as shown in the following command. If you have multiple devices connected, specify a target device by including the --device-id=serial-id flag.

bundletool build-apks --connected-device
--bundle=/MyApp/my_app.aab --output=/MyApp/my_app.apks

Generate and use device specification JSON files

bundletool can generate an APK set that targets a device configuration specified by a JSON file. To first generate a JSON file for a connected device, run the following command:

bundletool get-device-spec --output=/tmp/device-spec.json

bundletool creates a JSON file for your device in the tool's directory. You can then pass the file to bundletool to generate a set of APKs that target only the configuration described in that JSON file, as follows:

bundletool build-apks --device-spec=/MyApp/pixel2.json
--bundle=/MyApp/my_app.aab --output=/MyApp/my_app.apks

Manually create a device specification JSON

If you don't have access to the device for which you want to build a targeted APK set—for example, if you want to try your app with a device you don't have on hand—you can manually create a JSON file using the following format:

{
  "supportedAbis": ["arm64-v8a", "armeabi-v7a"],
  "supportedLocales": ["en", "fr"],
  "screenDensity": 640,
  "sdkVersion": 27
}

You can then pass this JSON to the bundle extract-apks command, as described in the previous section.

Extract device-specific APKs from an existing APK set

If you have an existing APK set and you want to extract from it a subset of APKs that target a specific device configuration, you can use the extract-apks command and specify a device specification JSON, as follows:

bundletool extract-apks
--apks=/MyApp/my_existing_APK_set.apks
--output-dir=/MyApp/my_pixel2_APK_set.apks
--device-spec=/MyApp/bundletool/pixel2.json

Measure the estimated download sizes of APKs in an APK set

To measure the estimated download sizes of APKs in an APK set as they would be served compressed over the wire, use the get-size total command:

bundletool get-size total --apks=/MyApp/my_app.apks

You can modify the behavior of the get-size total command using the following flags:

Table 2. Options for the get-size total command

Flag Description
--apks=path (Required) Specifies the path to the existing APK set file whose download size is being measured.
--device-spec=path Specifies the path to the device spec file (from get-device-spec or constructed manually) to use for matching. You can specify a partial path to evaluate a set of configurations.
--dimensions=dimensions Specifies the dimensions used when computing the size estimates. Accepts a comma-separated list of: SDK, ABI, SCREEN_DENSITY, and LANGUAGE. To measure across all dimensions, specify ALL.
--instant Measures the download size of the instant-enabled APKs instead of the installable APKs. By default, bundletool measures the installable APK download sizes.
--modules=modules Specifies a comma-separated list of modules in the APK set to consider in the measurement. The bundletool command automatically includes any dependent modules for the specified set. By default, the command measures the download size of all modules installed during the first download.

Additional resources

To learn more about using bundletool, watch App Bundles: Testing bundles with bundletool and the Play Console.