ftserver-android
Self-hosted search engine with web service to share discoveries with
...Check the file size after downloaded the Android APK.
https://sourceforge.net/projects/ftserver-android/files/
The Code Repository includes
FTServer Android Version Source Code (Android)
FTServer Java Server Version Source Code (Linux Windows)
FTServer .NET Server Version Source Code (Linux Windows)
https://sourceforge.net/p/ftserver-android/code/