A private messenger for Android.

Thunderbird for Android – Open Source Email App for Android (fka K-9 Mail)

Loop Habit Tracker, a mobile app for creating and maintaining long-term positive habits

Android application to analyze Wi-Fi signals.

Easy to use OpenStreetMap editor for Android

DAVx⁵ is an open-source CalDAV/CardDAV suite and sync app for Android. You can also access your online files (WebDAV) with it.

A tool for BLE environment monitoring. Find and track Bluetooth devices around, and get notified when the target device is detected.