bundletool

bundletool is the underlying tool that Android Studio, the Android Gradle plugin, and Google Play use to build an Android App Bundle, and convert an app bundle into the various APKs that are deployed to devices. bundletool is also available to you as a command line tool, so you can build app bundles yourself and recreate Google Play’s server-side build of your app’s APKs.

Download bundletool

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

Build an app bundle

You should use Android Studio and the Android plugin for Gradle to build and sign an Android App Bundle. However, if using the IDE is not an option (for example, because you’re 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, you should test how Google Play uses it to generate APKs and how those APKs behave when deployed to a device. There are two ways you should consider testing your app bundle: locally using the bundletool command line tool and through Google Play by uploading your bundle to the Play Console and using a test track. This section explains how to use bundletool to test your app bundle locally.

When bundletool generates APKs from your app bundle, it includes them 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 below.

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

If you want to deploy the APKs to a device, you need to also include your app’s signing information, as shown in the command below. If you do not 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 table below describes the various flags and options you can set when using the bundletool build-apks command in greater detail. Only --bundle and --output are required—all other flags are optional.

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, go to the section about how to deploy APKs to a connected device.
`--overwrite`	Include this flag if you want to overwrite any existing output file with the same 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`	Specifies the path to the deployment keystore used to sign the APKs. This flag is optional. If you don't include it, `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’s password. If you’re specifying a password in plain text, qualify it with `pass:`. If you’re passing 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’re specifying a password in plain text, qualify it with `pass:`. If you’re passing 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`	Use this flag to provide 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 Create and use device specification JSON files.
`--mode=universal`	Set the mode to `universal` if you want `bundletool` to build only a single APK that includes all of your app's code and resources such 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`	Use this flag to enable 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 looks for a compatible multi-APK and deploys it 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 below. (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’d rather not 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 below. (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 is capable of generating 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 directory the tool is located. You can then pass it 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, a friend wants 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:

Flag	Description
`--apks=path`	(Required) Specifies the path to the existing APK set file whose download size is 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, try the following resource.

Codelabs

Your First Android App Bundle, a codelab that explores the basic principles of Android App Bundles and shows you how to quickly get started with building your own using Android Studio. This codelab also explores how to test your app bundles using bundletool.