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.
StackPath - Secure Content Delivery Network, DDoS, WAF Service
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
Avast - Avast security software products are developed for Microsoft Windows, Mac OS X, Android and Linux users by AVAST Software.
APKMirror - Android Market and APK Downloads
Flexera Software Vulnerability Manager - Flexera Software Vulnerability Manager provides solutions to continuously track, identify and remediate vulnerable applications.