FOSS apps: free and open source

Free and open-source software: the source code is public under an open licence.

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Cyclic Alarms

Alarm app for shift schedules — repeats every N days, not just weekly
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Cycluna

Your cycle and the moon, tracked privately on your phone.
- Health & fitness
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
Czech Diacritic Keyboard

with caron and acute keys
- Productivity
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Czech for AnySoftKeyboard

AnySoftKeyboard Czech Language pack
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
D
DAAP

DAAP (Music/media sharing) Client
- Multimedia
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid Zapstore
DadosD

Generate Brazilian test IDs for development/test
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Daedalus

No root required Android DNS modifier and Hosts/DNSMasq resolver
- Security & privacy
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub
Dagger: Dota 2 Stats

Stay up-to-date with the latest Dota 2 matches, watch streams, and more.
- Games
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
Dahdidahdit — The Morse Trainer

An Actual Morse Code Trainer — Not Just A Morse Code Generator
- Education
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid IzzyOnDroid GitHub Zapstore
dahliaOS Calculator

Perform basic calculations
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub
Daily Dozen

Keep track of the foods that Dr Greger recommends in his book How Not to Die
- Health & fitness
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
Daily Pill — Medication Reminder

Reminder app for your daily medication. Easy to use and respects your privacy.
- Health & fitness
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub
Daily Screen Time

Track your daily screen time and regain control of your attention.
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid Zapstore
Daily Wallpapers

Daily Bing wallpapers for your home and lock screen
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid Zapstore
DailyAL

Full featured MyAnimeList client made with flutter
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
dandelion*

diaspora* social network client
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
dandelior*

diaspora* social network client
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Danish for AnySoftKeyboard

AnySoftKeyboard Danish Language pack
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
DankChat

A simple app to chat on Twitch.tv
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
DanXi

Maybe the best all-rounded service app for Fudan University students.
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid Zapstore
DAPNET

Send and read calls to and from DAPNET
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Dark Mode Live Wallpaper

Live wallpaper that respects dark theme mode
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
Dark theme

Activate dark theme on your device.
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
Dart Checker

Dart scoreboard/counter for physical dart matches
- Games
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid Zapstore
D
DartsTrainer

Cross-Platform app for all darts players
- Games
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Dashchan

Client for imageboards
- Communication
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub
DashPay Wallet

Have your Dash always with you, in your pocket!
- Finance
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid Zapstore
Data Monitor

Track all your data usage - at one place
- Internet
- FOSS
- Free
- In-app purchases
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub
DataBackup

Back up/Restore your data.
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid IzzyOnDroid GitHub Zapstore
Databag

A federated chat client designed for privacy and selfhosting.
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid Zapstore
Datamosh

Create live datamoshed videos with your camera
- Multimedia
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
DataStats

View bandwith usage
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid GitHub Zapstore
DataStopwatch

Stopwatch, but for data usage
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid
Datenspuren 2026 Schedule

Schedule for the Datenspuren conference at Zentralwerk Dresden
- Productivity
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid Zapstore
DAVx⁵

CalDAV/CardDAV Synchronization and Client
- Internet
- FOSS
- Free
- Paid
- In-app purchases
- No ads
- No tracking
- Android only
Google Play F-Droid IzzyOnDroid GitHub Zapstore
DAVY - Daika Anime Viewer because YOLO

Lightweight, open-source anime player for Android TV.
- Multimedia
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
Dawarich (Community)

Open Source Community Mobile Client for Dawarich By Sunstep
- Navigation
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid Zapstore
dawdle

Moodle client — e-learning platform
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid Zapstore
DayExam

Exam question management and learning tool with AI-powered document parsing.
- Education
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
DBase Downloader

Download video and music from 1,750+ sites with yt-dlp and FFmpeg
- Internet
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
DbCleaner for Whatsapp

Remove Whatsapp database files from external storage
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub
DBZ Battery Widget

View your battery status with your favorite DBZ character
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub
DCC++Throttle

Application to drive DCC-EX command station via Bluetooth
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
De Fide

Offline Catholic app for prayer, Scripture, novenas, and the Rosary.
- Education
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub Zapstore
De-Bloater

Use the power of Magisk/Kernel SU to de-bloat system applications systemless-ly
- System & tools
- FOSS
- Free
- Paid
- No ads
- No tracking
- Android only
Google Play F-Droid IzzyOnDroid GitHub Zapstore
De1984

Privacy-focused Firewall and Package Manager for Android devices
- System & tools
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid IzzyOnDroid GitHub Zapstore
DeadHash

Hashsum calculation utility
- Security & privacy
- FOSS
- Free
- No ads
- No tracking
- Android only
Google Play Aurora Store F-Droid IzzyOnDroid GitHub Zapstore
Deadlines

Simple app for managing deadlines
- Productivity
- FOSS
- Free
- No ads
- No tracking
- Android only
F-Droid GitHub