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.
Solid Explorer - Solid Explorer is a powerful Android file manager featuring access to most popular cloud storages, root access and easy extensibility.
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
MiXplorer - MiXplorer is a mobile app that was designed to make it easy to organize and manage the files on your Android device.
APKMirror - Android Market and APK Downloads
Cx File Explorer - Cx File Explorer is a free powerful file manager application with a clean and intuitive interface.