Chameleon is a CSS like framework for Android. Chameleon can read styles in JSON format and apply them on views in Android. Not only can you choose from the variety of styles provided by the library but also add your own styles by changing just one file.
The icing on the cake is, once set up, themes can be updated without pushing a new version of your app to the playstore. So, your users can see your changes on the fly.
A simple no Internet dialog and snackbar, which will automatically appear and disappear based on Internet connectivity status.
A simple android library that lets you easily query against the Proximity Beacon REST Api in a Reactive manner.