Useful Apps from F-Driod

General Usage

Document Viewer - View and read PDF files and books
Simple Gallery Pro - view, manage and edit your photos, videos, GIFs
VLC - video and music player
Organic Maps - community-driven maps & Navigation for travelers, tourists, cyclers & hikers
QKSMS - Replacement for the stock AOSP messaging app.
Fennec - Firefox with tracking removed
blabber.im - XMPP/Jabber Messenger for Android
Telegram FOSS - Client for the Telegram messaging platform
WhatsApp Web To Go - Mobile Client for Whatsapp Web
Tasks.org - To-Do Lists & Reminders
SecScanQR - QR code scanner/generator
DNS66 - Block ads on pages
RadioDroid - listen to online raido stations from accross the world.
Fritter - twitter client/reader with device-local subscriptions

Pro Users

OsmAnd~ - advanced map viewing & navigation for offline and online OSM maps
RedReader - unofficial, open-source client for Reddit
Quillnote - device local notes that you can sync using syncthing
Syncthing - decentralized file synchronization
Aegis - secure and 2FA app to manage TOTP tokens for online services
RethinkDNS - Block ads on pages
Vigilante - know when a third-party app uses your device camera/microphone
My App List - Saves a list of installed or selected applications as XML, HTML or plaintext file

Developers / Sysadmins

Termux - Terminal emulator with packages
PCAPdroid - network monitor and traffic dump tool for your device
Editor - Simple generic text editor
WiFiAnalyzer - checking WiFi network status, signal strength and identifying channels
App Manager - a full-featured package manager for android.
Stanley - Application explorer for developers

Notes:

RadioDroid Uses internet radio stations database: https://www.radio-browser.info

Signal

Signal is not included in F-droid repo but you can directly download and install apk from:

https://signal.org/android/apk/

Briar

Peer-to-peer encrypted messaging.

https://briarproject.org/installing-briar-via-f-droid/

Librera PRO

Librera Reader is a highly customizable and feature-rich application
for reading e-books in PDF, EPUB, MOBI, DjVu, FB2, TXT, RTF, AZW, AZW3, HTML, CBZ, CBR, DOC, DOCX, etc. formats

Termux

To make termux ask for storage permission, open termux and run following then restart termux:

termux-setup-storage