SecondsClock

Clock with seconds as widget or fullscreenGPL-3.0-or-later

Clock31

Clock + Calendar combo widget for AndroidGPL-3.0-only

Hayago

A minimalist go/chess clockMIT

Giant Stopwatch

Stopwatch and clock with giant digitsMIT

Just 24 Hours

A free and open source app that shows a large digital clockMIT

Japanese Traditional Time

Clock widgetMIT

Alarm Klock

An alarm clockApache-2.0

RomanDigital

Digital Clock App and Widget with Roman Numeral DisplayApache-2.0

Dynamic Night Light

Low brightness clockApache-2.0

Klock

A simple chess based clock applicationGPL-3.0-or-later

Schule

simple educational practice game for kids and adults: maths, clock, spellingGPL-3.0-or-later

NightDream

Clock, screensaver & radio with dynamic brightness & custom layouts.GPL-3.0-or-later

Octal Sun Time

A clock for solar time in the octal number systemGPL-3.0-only

Valentin's PowerTools #036 - Ease The Waiting

A mix between a calendar and a clock that makes you wait faster.GPL-3.0-only

Terminightor

Alarm clock based on NFC tagsGPL-3.0-or-later

Fokus Launcher

Minimal launcher with clock, weather, fast app search, and gesture navigation.GPL-3.0-only

QRAlarm

Disable alarms with a QR scannerGPL-3.0-only

Suntimes

Sunlight and moonlight information (clock, alarms, tiles, and widgets).GPL-3.0-or-later

Warpclock

Quick shortcut for setting alarms based on your preferred amount of sleep.GPL-3.0-only

Chrono

Modern and powerful clock, alarms, timer and stopwatch.GPL-3.0-or-later