Zoom - Equip your team with tools designed to collaborate, connect, and engage with teammates and customers, no matter where you’re located, all in one platform.
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.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
APKMirror - Android Market and APK Downloads