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WebviewJS on Android is an experimental platform target that embeds a native WebView inside an Android Activity using Tao’s Android backend. It supports both 64-bit ARM (aarch64) and 32-bit ARM (armv7) devices, making it compatible with the vast majority of Android hardware. The API surface is intentionally minimal — most windowing primitives do not apply to Android, and the two Android-specific methods (androidContentRect() and androidConfig()) give you the information you need to integrate the webview with the rest of your native UI.
Android support is experimental. Pre-built binaries may not be available for all minor versions. APIs and behaviour may change without a semver-breaking release. Test on physical devices before shipping.

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Supported Architectures

WebviewJS targets the two most common Android CPU architectures:
ArchitectureAndroid target triple
ARM64 (64-bit)aarch64-linux-android
ARMv7 (32-bit)armv7-linux-androideabi
x86 and x86_64 Android targets (used in the emulator) are not currently supported. Use a physical ARM device or an ARM-capable emulator (e.g. Apple Silicon Mac’s Android emulator with ARM images).

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Android-Specific Runtime APIs

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androidContentRect()

androidContentRect() returns the current native content inset rectangle — the area within the Activity window that the WebView occupies, in pixels relative to the Activity’s top-left corner. This is useful for laying out additional native views (e.g. a bottom navigation bar) alongside the webview: 
const rect = win.androidContentRect();

console.log(rect);
// { left: 0, top: 0, right: 1080, bottom: 1920 }

const width  = rect.right  - rect.left;
const height = rect.bottom - rect.top;
console.log(`Content area: ${width}×${height} px`);
The returned object conforms to AndroidContentRect: 
interface AndroidContentRect {
  left:   number;  // left edge in pixels
  top:    number;  // top edge in pixels
  right:  number;  // right edge in pixels
  bottom: number;  // bottom edge in pixels
}

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androidConfig()

androidConfig() returns the current Android configuration as a diagnostic string. This is intended for debugging and logging — for example, to record device locale, screen density, and orientation at crash time: 
const config = win.androidConfig();
console.log('Android config:', config);
// e.g. "mcc=0 mnc=0 locale=en_US touchscreen=3 ..."
androidConfig() is a diagnostic utility and should not be used to make layout decisions. Use androidContentRect() for layout, and standard web APIs (screen.width, window.devicePixelRatio, etc.) for responsive design.

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Unsupported APIs on Android

Some WebviewJS features are not available on Android and will throw an error or silently no-op:
app.createTrayIcon() returns an error on Android — the Android platform has no system tray concept. Guard tray creation with a platform check if your code targets multiple platforms.
win.openFileDialog() is not implemented on Android. Use the Web File API (<input type="file">) or a custom protocol handler to access the filesystem.

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Configuration Tips

1

Use logical pixels for layout

Android devices vary widely in pixel density. Always pass logical: true to setSize() and setPosition(), or set logical: true in BrowserWindowOptions, so your layout uses density-independent pixels.
const win = app.createBrowserWindow({ logical: true, width: 360, height: 640 });
2

Load content via a custom protocol

Android’s WebView has restrictions on file: access to app-internal assets. Register a custom protocol via win._registerProtocol() to serve your HTML, CSS, and JS, then load from it:
webview.loadUrl('app://localhost/index.html');
3

React to content rect changes

The system keyboard, navigation bars, and notches can change the content rect dynamically. Poll androidContentRect() via window events to adapt your layout:
win._onWindowEvent((payload) => {
  const rect = win.androidContentRect();
  console.log('New content area:', rect);
});

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Known Limitations

  • win.setProgressBar() is not implemented on Android.
  • win.setContentProtection() behaviour depends on the OEM’s WebView implementation.
  • win.setSkipTaskbar() is a no-op (Android has no taskbar).
  • Window transparency (transparent: true) requires the Activity to be configured with a transparent theme in the Android manifest; WebviewJS cannot set this at runtime.

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