WebView Build Instructions

Building WebView for the first time? Please see the quick start guide first.


This is meant to be a comprehensive guide for building WebView, within the limits of what is possible in a public chromium checkout. While this is sufficient for most cases, Googlers may wish to consult internal instructions to get a checkout including closed-source code, which is necessary if:

  • You work on features depending on this closed-source code
  • You want to use the “downstream” targets (ex. system_webview_google_apk), or
  • You need to install on a preview Android release

System requirements, tools, etc.

See general Android instructions for:

Device setup

For the minimum requirements, please see Device Setup.

Setting up the build

Configure GN args (run gn args out/Default) as follows:

target_os = "android"

# See "Figuring out target_cpu" below
target_cpu = "arm64"

# Not always necessary, see "Changing package name" below
system_webview_package_name = "..."

# Optional: speeds up fresh builds (Googlers-only)
use_goma = true

Figuring out target_cpu

Please see the Chromium instructions.

Building WebView

Similarly to Chrome, WebView can be compiled with a variety of build targets.

TODO(https://crbug.com/956315): document the differences between each target.

First, you should figure out your device's integer API level, which determines which build targets will be compatible with the version of the OS on your device:

adb shell getprop ro.build.version.sdk
Tip: you can convert the API level integer to the release's dessert codename with this table. This developer guide uses API integers and release letters interchangeably.

Then you can build one of the following targets:

# For L+ (21+) devices (if on N-P, see "Important Notes for N-P")
autoninja -C out/Default system_webview_apk

# For N-P (24-28) devices (not including TV/car devices)
autoninja -C out/Default monochrome_public_apk

# For Q+ (29+) devices
autoninja -C out/Default trichrome_webview_apk
Tip: building trichrome_webview_apk will automatically build its dependencies (i.e., trichrome_library_apk).

Changing package name

Unlike most Android apps, WebView is part of the Android framework. One of the consequences of this is that the WebView implementation on the device can only be provided by a predetermined set of package names (see details). Depending on the chosen build target, you may need to change the package name to match one of the following:

API levelHas GMS vs. AOSP?Allowed package names
L-MAOSPcom.android.webview (default, preinstalled)
L-MHas GMScom.google.android.webview (default, preinstalled)
N-PAOSPcom.android.webview (default, preinstalled)
N-P (TV/car devices)Has GMScom.google.android.webview (default, preinstalled)
N-P (other devices)Has GMScom.android.chrome (default, preinstalled)
com.google.android.apps.chrome (only userdebug/eng)
com.google.android.webview (preinstalled) (see Important notes for N-P)
>= QAOSPcom.android.webview (default, preinstalled)
>= QHas GMScom.google.android.webview (default, preinstalled)
com.google.android.webview.debug (only userdebug/eng)
com.android.webview (only userdebug/eng)

system_webview_apk and trichrome_webview_apk use com.android.webview as their package name by default. If your device allows this package name, continue to the next section. Otherwise, you can change the package name for either target by setting the system_webview_package_name GN arg (ex. system_webview_package_name = "com.google.android.webview").

monochrome_public_apk‘s package name defaults to org.chromium.chrome. Because this not accepted by any build of the OS, you’ll want to change this with the GN arg chrome_public_manifest_package = "com.google.android.apps.chrome", or choose system_webview_apk instead.

See internal instructions for the Google-internal variants of the build targets (system_webview_google_apk, monochrome_apk, trichrome_webview_google_apk).

Note: TV/car devices have a bug where the release key signed WebView is preinstalled on all Android images, even those signed with dev-keys. Because humans cannot access release keys (use_signing_keys = true provides “developer test keys,” not release keys), you must remove the preinstalled WebView (see below).

Removing preinstalled WebView

If WebView is preinstalled (under the chosen package name) in the device‘s system image, you’ll also need to remove the preinstalled APK (otherwise, you'll see signature mismatches when installing). You can skip this step if either of the following is true:

Otherwise, you can remove the preinstalled WebView like so:

If you're using an emulator, make sure to start it with -writable-system before removing the preinstalled WebView.

If the script doesn't work, see the manual steps.

Important notes for N-P

This functionality was added in N and removed in Q, so you should skip this if your device is L-M or >= Q.

If you have an Android build from N-P (and, it uses the Google WebView configuration), then the com.google.android.webview package will be disabled by default. More significantly, installing a locally compiled APK won't work, since the on-device WebViewUpdateService will immediately uninstall such updates. To unblock local development, you can re-enable the WebView package and disable this behavior from WebViewUpdateService with:

# Only necessary if you're using the 'com.google.android.webview' package name
adb shell cmd webviewupdate enable-redundant-packages

Installing WebView and switching provider

For help connecting your Android device, see the Chromium instructions.

You can install a locally compiled APK like so (substitute system_webview_apk with the chosen build target name):

# Install the APK
out/Default/bin/system_webview_apk install

# Only on N+: tell Android platform to load a WebView implementation from this APK
out/Default/bin/system_webview_apk set-webview-provider
Tip: out/Default/bin/trichrome_webview_apk install will handle installing all its dependencies (i.e., trichrome_library_apk), so you can interact with this target the same as you would interact with any other WebView build target.

Start running an app

See Start running an app from the quick start.


Please see the Troubleshooting section in the quick start.

TODO(ntfschr): document cases here which could arise generally, but wouldn't for the quick start.