Fossify Clock Beta
Open-source alarm, timer and stopwatch app with no ads and offline use
Alarm clock apps for Android
Four alarm clock apps for Android are covered here: Fossify Clock Beta, Clock, Suntimes and Alarmy.
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The first three are free, show no ads and are open source under GPL-3.0-only, Apache-2.0 or GPL-3.0-or-later. Their downloads are small, from 6.9 MB to 11.2 MB, and all were updated in 2026.
Alarmy is a different kind of product. Its audience is far larger, but it carries ads and in-app purchases. No license or file size is given for it, and the three open-source apps are not ranked against each other.
Apps in this category
Clock
Free offline alarm clock with math dismissal, no ads, 6.9 MB, Android 6.0+
Suntimes
Open-source sun and moon clock with sunrise alarms, no ads, 11.2 MB
Alarmy
Alarm clock that makes heavy sleepers scan, solve or squat to wake
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Top 5 picks
Fossify Clock Beta
Fossify Clock Beta, from developer Fossify, is version 1.6.0 and was updated on February 2, 2026. It weighs 8.7 MB, shows no ads and costs nothing under the GPL-3.0-only license. It is a light, open-source clock with the essential features, and it has the oldest update date of the three open-source apps.
Clock
Clock is version 2.34, updated on October 22, 2026, and is the smallest app here at 6.9 MB. It uses the Apache-2.0 license, shows no ads, and has alarm, clock, timer and stopwatch modes. It uses no internet permission. Alarms can be set for a date or time zone and dismissed by flip, shake or math problems.
Suntimes
Suntimes, version 0.17.6, was updated on October 29, 2026 and takes 11.2 MB, the largest of the three open-source apps. It pairs a clock and alarms with sunrise, sunset, twilight and moon phase times. The times are approximate, GPS is optional and no network is needed. It is free, ad-free and GPL-3.0-or-later.
Alarmy
Alarmy, from Delightroom, is version 26.42.0, updated on November 4, 2026. Its alarms rely on missions such as barcode or photo, math, typing, shake or squat tasks, so you have to get up and do something before the sound stops. It is free to download but contains ads and in-app purchases.
Questions and answers
Which of these alarm clock apps show no ads?
Fossify Clock Beta, Clock and Suntimes are listed without ads, and all three are free. Alarmy is also free to download, but it has ads and in-app purchases.
Can any of them run without an internet connection?
Clock uses no internet permission. Suntimes does not need network connectivity, and GPS is optional.
Which apps make you do something to turn off the alarm?
Alarmy uses missions such as barcode or photo scans, math, typing, shake and squat. Clock supports flip and shake actions, the power or volume buttons, and math problems for dismissing or snoozing.
Related categories
Best-of lists
Start with how you wake up. If you only want a plain alarm with a timer and stopwatch, Clock covers those modes at 6.9 MB with no ads. If you need a task to get you out of bed, Alarmy has the largest set of missions, though it adds ads and in-app purchases.
Suntimes suits people who also care about sunrise or moon times, but its own listing calls the times approximate. Whichever app you install, set a test alarm for a few minutes ahead and confirm it sounds as expected before relying on it overnight.