TapTap - Read, Write and Share addictive chat stories for free with TapTap.
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.
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
Aptoide - Aptoide is a third party replacement for the traditional Google Play Store.
APKMirror - Android Market and APK Downloads
Rubyapks - Rubyapks is a free web-based app store that is specially designed for Indie games lovers.