A custom widget that looks like a task manager on Android 5.0.
Retrofit is an wonderful network library to deal with api's and Rx java can be used to do async task operations effectively. Using retrofit with RxJava will results in seamless network calls in mainthread. Retrofit can be used without RxJava, though to perform huge api calling and to do api calls in background, they pair a better combination.
The best qualitative analytics tool for your Android & iOS Apps. UserExperior provide video replay of your user sessions on your app and also provides touch heat maps of your users interaction on your app screens.