• Nextcloud. Keep everything under control: Contacts, calendars, tasks, files, documents… whatever you want.

• F-Droid
• Aurora

• AndOTP (100% opensource)

• DAVx5 (Mandatory if you use nextcloud)

• K9 Mail
• Zoho Mail (only if you use zoho.com mail of course)

• Etar

• Simple Gallery pro

• Keepassdroid (Recommended If you want to use 100% opensourced apps)
• KeePassDX (Simple but powerful)
• keepass2android (recommended, use aurora to install it)

• Newpipe

• VLC (of course)

OLD: https://telegram.org/android → Use their own APK, not the google play one which is limited (read their own disclaimer in the linked page) FUc*ING PREMIUM AND all their SH*T!!!!!!!!!!!!!!!!!!!!!!!!!

FOSS (free and opensource software) alternatives:

• https://github.com/Forkgram (recommended, it has anti-premium features)
• https://github.com/Telegram-FOSS-Team/Telegram-FOSS

• LuckyPatcher (got root? )

• Tor browser (tor surfing the world)
• Tor "vpn" (everything through tor)
• Tracker Control the best application to block write here the big-brother you want on any application with 100% customizable settings (will be a bit hardcore at the beginning)