- RxJava - reactive programming (see also Introduction to ReactiveX)
- Dagger - dependency injection (note: this is the Google fork (version 2). Version 1 is maintained by Square and seems to be still alive)
- Gson - JSON (de)serialization to/from Java objects
- DBFlow - ORM
- Volley - asynchronous networking for Android (GitHub unofficial mirror, Maven-enabled
- OkHttp - An HTTP & HTTP/2 client for Android and Java applications
- Retrofit - turns your HTTP API into a Java interface
Discussion about OkHttp, Retrofit, Volley and how to do some non-standard integrations:
- http://stackoverflow.com/questions/16902716/comparison-of-android-networking-libraries-okhttp-retrofit-volley
- https://medium.com/android-news/android-networking-i-okhttp-volley-and-gson-72004efff196#.yh5gfr2pz
- Butter Knife - Field and method binding for Android views
- RoboGuice - view injection and a lot of other boilerplate-eliminating goodies
I'm not sure which of these actually helped me 😛