F-Droid - F-Droid is an interesting alternative for Android users who want to try something different and not have to use the Goole Play store all the time.
MySQL - The world's most popular open source database
Aptoide - Aptoide is a third party replacement for the traditional Google Play Store.
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
APK Pure - Download apk for Android with APKPure APK downloader. NoAds, Faster apk downloads and apk file update speed. Best of all, it's free
SQLite - SQLite Home Page