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

Aurora Store - Aurora is a FOSS Play Store client that does not require a Google Account to download directly from Play Store. However you can login with your Google Account to download your already paid apps!

Website 2 APK Builder - Convert your HTML, CSS, JS and all other web content into an Android App within seconds.

Aptoide - Aptoide is a third party replacement for the traditional Google Play Store.

APKMirror - Android Market and APK Downloads