CanIWebView Apps & Resources
CanIAndroidWebView
CanIAndroidWebView is an open source app built to test your content inside Android WebViews. You can try different configurations and see how your content behaves in the Android WebView. It's also useful to reproduce issues and report bugs.
The app is available on the Google Play Store and the source code and issue tracker is available on GitHub.
If you find a bug in the Android WebView you can submit an issue on the Chromium issue tracker or on the Google issue tracker.

CanIWKWebView
CanIWKWebView is an open source app built to test your content inside iOS WebViews. You can try different configurations and see how your content behaves in the iOS WebView. It's also useful to reproduce issues and report bugs.
The app is available on the App Store and the source code and issue tracker is available on GitHub.
If you find a bug in the iOS WebView you can submit an issue on the Apple bug reporter or WebKit issue tracker Bugzilla.
CanIWebView2
CanIWWebView2 is an open source app built to test your content inside WebView2. It's also useful to reproduce issues and report bugs.
The source code and issue tracker is available on GitHub.
If you find a bug in the WebView you can submit an issue on the Microsoft Edge WebView2 Feedback repository on GitHub.
Acknowledgements
Development of these apps is part of a project funded by NLnet Foundation under its NGI Mobifree Fund.