APK Studio - APK Studio is an open-source Integrated Development Environment that allows you to recompile and decompile Android applications with its unified interface.
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
JADX - JADX is a decompilation tool that can produce Java Source code from Dex and Apk files, being capable of providing human-readable java classes, it reverses AndroidManifest.
ApkPlayGame.com - Android Gaming at its best! Download thousands of Android Games fast, free and easy apk download! All game genres including 3D, HD, Open World, FPS, Battle Royale, Offline, Online Multiplayer, Time Killer...
Apktool - Apktool is an all-in-one tool that can extract all the resources inside an APK.
APKMirror - Android Market and APK Downloads