Uptodown - Uptodown is a mobile app and website that lets you download games and apps to users on most of the major platforms.
GNOME Software - A application for installing apps and updates.
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
AppsHive - Curate your app according to Subcategories, Profession, and Location.
APKMirror - Android Market and APK Downloads
Aptoide - Aptoide is a third party replacement for the traditional Google Play Store.