android-youtube-player is a stable and customizable open source YouTube player for Android. It provides a simple View that can be easily integrated in every Activity/Fragment.
To interact with YouTube the library uses the IFrame Player API, inside of a WebView, therefore the YouTube app is not required on the user's device and there are no issues with YouTube Terms of Service.
The web UI of the IFrame Player player is hidden. Instead, a native UI built on top of Android is used to interact with the player, providing a native experience to the users.
This library also provides a Chromecast YouTube player, that you can use to cast YouTube videos from your app to a Chromecast device.
Why does this library exist?
The official library provided by Google to integrate YouTube videos in Android apps is the YouTube Android Player API. The official library is quite buggy (some bugs are 5+ years old) and lacks in support from Google. I found it to be quite unreliable and therefore unusable in production.
This, added to its limited options for customization and lack of Chromecast support, lead me to the development of this open source library.
A lengthier explanation to why you may want to consider using an alternative to the official YouTube player is written in this Medium post.
A list of published apps that are using this library: (let me know if you want to add your app to this list)