Pathmatics - Pathmatics provides actionable display and mobile intelligence to many brands, agencies, publishers, and advertisers.
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.
Mobile Action - Mobile Data Intelligence & Actionable Insights.
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
Flurry - Personalizing The Mobile Experience
APKMirror - Android Market and APK Downloads