Android (with F-Droid)

You need to enable “unknown sources” in the security settings of your device to install F-Droid. This isn’t something bad, it just allows you to install apps from somewhere else as the Play Store.

App Store

• F-Droid free (GPL)

Play Store Downloaders

• Aurora Store free (GPL)
• Yalp Store free (GPL)

Web Browser

• Firefox free (MPL, GPL, LGPL)
• Firefox Klar free (MPL)

Browser Extensions

• uBlock Origin free (GPL)
• EFF Privacy Badger free (GPL)

E-Mail Client

• K-9 Mail (recommended) free (apache)

E-Mail Encryption

• OpenKeychain (for K-9 Mail) (recommended) free (GPL)

Messenger

• Threema payed
• Telegram free (GPL)
• WhatsApp gratis

Map

• OsmAnd~ (recommended) free (GPL)

Media Player

• VLC for Android (recommended) free (GPL, LGPL)

Podcast Manager & Player

• AntennaPod free (MIT)

File Managers

• FX gratis
• Total Commander gratis

PDF Viewer

• MuPDF Viewer free (AGPL)

Mathematics

• GeoGebra Graphing Calculator gratis
• GeoGebra Geometry gratis
• GeoGebra 3D Graphing gratis

pkpass Viewers

• PassAndroid free (GPL)

Public Transport

• Transportr (choose ÖBB for Austria) free (GPL)
• ÖBB Scotty (Austria only) gratis

What is the difference between free and gratis?

Free means free as in freedom while gratis only means that you don’t have to pay for it.