oandbackup - Make backups of selected apps on your device and restore from those backups.
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.
Super Backup & Restore - Super Backup & Restore app allows users to backup all their stuff such as pictures, videos, apps, text messages, contacts, call history, and calendar data, etc.
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
Tenorshare WhatsApp Transfer - Transfer/Backup/Restore WhatsApp on iPhone/Android with One Click
APKMirror - Android Market and APK Downloads