Calendar

284 open source Calendar apps

10-bit Clock Widget
APK
10-bit Clock Widget presents current time on your home screen using binary coded decimals. Features - 12-hour display format (default) - 24-hour display format - Use custom colours 10-bit Clock Widget is free and open-source software. https://github.com/ashutoshgngwr/10-bitClockWidget
F-DroidGitHub
16-bit Clock Widget
APK
Binary Clock composed of a 4x4 grid of dots. It works by dividing the day into 16 bits, or 65536 parts. That makes each "second", or bit, last exactly 1.318359375 real seconds.
F-DroidGitHub
3
39C3 Schedule
APK
Conference program app for the Chaos Communication Congress The 39th Chaos Communication Congress (39C3) takes place in Hamburg on 27–30 Dec 2025, and is the 2025 edition of the annual four-day conference on technology, society and utopia organized by the Chaos Computer Club (CCC) and volunteers. Congress offers lectures and workshops and various sessions on a multitude of topics including (but not limited to) information technology and generally a critical-creative attitude towards technology and the discussion about the effects of technological advances on society. Starting in 1984, Congress has been organized by the community and appreciates all kinds of participation. You are encouraged to contribute by volunteering, setting up and hosting hands-on and self-organized sessions with the other components of your assembly or presenting your own projects to fellow hackers. https://events.ccc.de/congress/2025/ Features * View program by day and rooms (side by side) * Custom grid layout for smartphones (try landscape mode 🙃) and tablets * Read detailed descriptions (speaker names, start time, room name, links, ...) of sessions * Search and filter through all sessions * Add sessions to favorites list * Export favorites list * Setup alarms for individual sessions * Add sessions to your personal calendar * Share a website link to an session with others * Keep track of program changes * Automatic program updates (configurable in settings) * Vote and leave comments on talks and workshops * Integration with the c3nav indoor navigation project https://c3nav.de * Integration with the Engelsystem project https://engel.events.ccc.de - Online tool for coordinating helpers and shifts on large events * Integration with the Chaosflix https://github.com/NiciDieNase/chaosflix - Android app for http://media.ccc.de, share Fahrplan favorites with Chaosflix to import them as bookmarks 🔤 Supported languages (Session descriptions excluded) * Danish * Dutch * English * Finnish * French * German * German (Austria) * Italian * Japanese * Lithuanian * Polish * Portuguese (Brazil) * Portuguese (Portugal) * Russian * Spanish * Swedish * Turkish 💡 Questions regarding the content can only be answered by the content team of the Congress. This app simply offers a way to consume and personalize the conference schedule. 💣 Bug reports are very welcome. It would be awesome if you can describe how to reproduce the particular error. The issue tracker can be found here: https://github.com/EventFahrplan/EventFahrplan/issues 🎨 39C3 Power Cycles. Design by Nina Bender and Bernd Volmer
F-DroidGitHub
Achie
APK
The app for registering achievements (Achies) The achievements need to be countable Supported loading a picture in achievement adding Example: Date field: Oct, 16 2022 (filling automatically) Object field: creating app Type field: Working for creating a Achie App Measure: hours per day Count: 5
F-DroidGitHub
ActivityWatch
APK
ActivityWatch is an open-source cross-platform application that tracks how you spend time on your devices, and keeps you in control of your data. It is the same ActivityWatch you know and love, but for Android! It builds on the same core as the desktop version, enabling us to offer the same features whichever platform you are on. Note about accessibility permission: the app allows users to optionally grant the accessibility permission to enable collection of browsing history, by tracking URLs from supported browsers. You can report issues and view the source code on GitHub: https://github.com/ActivityWatch/aw-android
F-DroidGitHub
AeonDroid
APK
Planetary hours and astrological transit app. Also keeps track of Void of Course moons and moon phases.
F-DroidGitHub
Al-Azan - Prayer Times
APK
Privacy focused ad-free open-source muslim Adhan (islamic prayer times) and Qibla app App features: * Ad-Free * Doesn't use any kind of trackers * Open-source * You can search for your location offline Or use GPS * Set custom Adhan audio * Select different Adhan audio for Fajr namaz * In addition to five daily prayers, it has settings for Sunrise, Sunset, Midnight and Night Prayer (Tahajjud) * Many options for Adhan (اذان) calculation * Light and Dark theme * Hide times you don't need * Set reminders before or after a prayer time * Homescreen and notification Widgets * Qibla finder * Qada counter * Is localized in English, Persian, Arabic, Turkish, Indonesian, French, Urdu, Hindi, German, Bosnian, Vietnamese, Bangla Open-Source repository: https://github.com/meypod/al-azan/ Since we don't use any kind of tracker or crash analytics, Please report any problem or suggestion you have on our GitHub repo: https://github.com/meypod/al-azan/issues
F-DroidGitHub
Alarm Clock
APK
A simple alarm clock application that requires that you solve a math problem to deactivate the alarm.
F-DroidGitHub
A
Alarm Klock
APK
* Global and per-alarm settings * Repeats for days of the week * Ringtone and/or vibrate * Use MP3s/Media library as alarms * Variable snooze time * Variable volume adjustment * Localizations: it, nl, pt, de, sr, hr, fr, es
F-DroidGitHub
Always On Clock
APK
displays the date and time on your screen. thats all.
F-DroidGitHub
Analog Clock Widget
APK
Simple analog clock widget. It is resizable and has a clean dial. It uses the built-in AnalogClock widget of Android with a custom dial.
F-DroidGitHub
Another Widget
APK
A widget app for Android devices, providing various widgets for displaying weather, calendar events, and other information on the home screen.
GitHub
Anstop
APK
A simple stopwatch, that also supports lap timing and a countdown timer. The countdown timer doesn't make an alarm so an eye will have to be kept on it.
F-DroidGitHub
Anton Widget
APK
The agenda widget is formatted in a space-efficient way, displaying each event's location and calendar colour. Birthday events from Outlook and Facebook can be displayed separately.
F-DroidGitHub
Attendance Viewer
APK
Students of JUET and JIIT-128 can view class attendance. It visualizes the attendance in a streamlined manner, along with additional details for each subject, providing details about the subject. You can also set a threshold attendance which helps you in maintaining the attendance.
F-DroidGitHub
BBQ Timer
APK
Combined interval timer/stopwatch = periodic alarms + elapsed time.Reminds you periodically to turn the food and tracks the total cooking time.Quick access via lock screen notification, pull-down notification, and home screen widget.Editable menu of interval times. Quickly access your favorite timers with notes.Changeable alarms while it’s running.No ads.Type in the interval time: minutes, minutes:seconds, or hours:minutes:seconds.Example intervals10 = 10 minutes7:30 = 7 minutes, 30 seconds3:15:00 = 3 hours, 15 minutesShort forms12:00 = 12:0 = 12: = 12 = 12 minutes0:09 = :9 = 9 seconds2:00:00 = 2:0:0 = 2:: = 120 = 2 hoursTipsTap the checkbox to turn the periodic reminder alarms on/off.Tap the time display to cycle between stopped → running → paused → stopped.Add the BBQ Timer widget to the home screen.Tap the widget’s elapsed time to start/pause/stop.Tap the widget’s background or its countdown time to open the app.Resize the widget (long-press it then drag its resize handles) to see more or less info.To remove the widget, long-press and drag it to “× Remove”.While BBQ Timer is running or paused, it appears on the lock screen and in the pull-down notification so you can see and control it in those places.To put it on the lock screen, put it in Pause or Play mode by tapping buttons in the app or the home screen widget.Long-press the app’s home screen icon, then tap the “Pause at 00:00” shortcut (on Android 7.1+) to make it Paused and ready on the lock screen.Tap ▲ in the alarm interval text field for the menu of interval times.Tap “Edit these intervals…” in the menu to customize the menu.Long-press ▲ to customize the menu.The app, home screen widget, and pull-down notification show the countdown interval time as well as the total elapsed time (requires Android 7+).In the app, the phone’s volume keys adjust the Alarm volume.You can change BBQ Timer’s “Alarm” sound in Settings / Notifications. Don’t pick “None” if you want to hear the interval alarms. To restore the app’s cowbell sound, uninstall and reinstall the app.Note: These System Settings are required to hear and see BBQ Timer alarms:Audible “Alarm volume” level.Lock screen / Show all or non-private notifications.Apps / BBQ Timer “Show notifications”, not Silent. (Optionally override “Do Not Disturb”.)Apps / BBQ Timer “Alarm” notification category / “Show notifications”, not “Silent”, “Make sound and pop on screen”, sound choice not “None”, Importance “High” or higher to hear and see on the lock screen and in the notification area.Apps / Special app access / Alarms & reminders / Allowed.Notifications / App settings / BBQ Timer / On.
GitHubIzzyOnDroid
Baby Buddy for Android
APK
This app allows you to quickly log activities on the Open-Source website Baby Buddy (https://github.com/babybuddy/babybuddy). You need to host your own Baby Buddy server to use the app.With the app you can log events with fewer button-presses than when using the web interface: Quickly track your baby's feedings, sleep phases, tummy-time sessions, and diaper changes and use the history for an easy overview of the latest events.The app is optimized to be used by multiple people on multiple devices so that event tracking can be shared among different caregivers.Third Party AttributionsThe application contains the following media from www.flaticon.com, licensed under their attributions license for free use:Poop icons created by Good Ware - FlaticonDiaper icons created by Good Ware - FlaticonSleep icons created by Good Ware - FlaticonHumidity icons created by bqlqn - FlaticonNote icons created by Freepik - FlaticonCrawl icons created by Freepik - FlaticonBaby food icons created by Freepik - FlaticonBaby bottle icons created by juicy_fish - FlaticonBreast-pump icons created by srip - FlaticonLicense and project pageThis software is open source software developed under the MIT License. The license and source code are available on GitHub: - https://github.com/MrApplejuice/BabyBuddyAndroid/
GitHubIzzyOnDroid
BetterCounter
APK
- Track good and bad habits (eg: exercising, smoking, drinking...) - Track when's the last time you did something (eg: water your plants, change your bedsheets, poop...) - Count your lives in MtG Features: - Records the date and time of each individual counter increase. - Graphs your data over time and calculates statistics. - Lets you export your data (eg: to analyze it with your choice of tools). - Your data is never sent to any server (except for Google's app backup, if enabled). - Simple as hell and will stay this way.
F-DroidGitHub
Bewegungsmelder
APK
Companion app for Bewegungsmelder, a website focusing on concerts and other events around Hamburg, Germany.
F-DroidGitHub
Birday - Birthday Manager
APK
Introduction 👋 This app was created to remember and manage events in a simple and effective way. The app contains some basic personalization options and an introduction, plus some new resources like animated vector drawables and the automatic dark/light theme. Support and updates are guaranteed! Why should I use Birday? 😕 Well, I'll tell you 3 main reasons: It can help you to remember every birthday in the moment you prefer! It will cost just a few MB of storage! It's beautiful, full of animations and simple to use! Birday allows you to import the events directly from your contacts or calendar, with a simple favorite system and a set of stats to discover! if you're starting to develop apps and you need an app to look at, to find some inspiration and tricks: click on the GitHub link, and the Birday source code is served! Features 🎂 Simple events timeline, with the next date and the name of each person Normal/favorite/ignored system, to aggregate your favorite events and see more information Overview screen and a lot of basic and advanced settings Import birthdays from contacts or calendar with basic duplicate detection, select what to import Backup your events easily, in native, csv or json format, and choose where to save the backup 30+ language available. If you don't see your language, you can translate the app yourself! Easily delete, modify or share every event Each favorite event has an handy note field Customizable notification the day of the event, and additional notification(s)! Light, dark and black Amoled theme; Material3 Expressive Selectable accent and Monet accent (12 choices) Hide and unhide the top cards for maximum ui flexibility A quick search bar, yearly overview and type selector! 2 customizable widgets First introduction and beautiful animations including an animated notification icon Many possible customization and options Please note: the notification system relies on the Android OS resources, thus some manufacturers may cause malfunctions. The reason is that some Xiaomi, Huawei and Oneplus devices kill the apps instead of simply closing it, or block the automatic startup of the app process. I can't fix this, but you can find more information on dontkillmyapp.com.
F-DroidGitHubIzzyOnDroid
BirthDayDroid
APK
Free! No Ads! Opensource :D! BirthDayDroid is a simple Android application to help you to remember your contact's birthdays. It scans your local contact list looking for birthdays. When it finds it, it will show you the contact's age, sign, days until her/his birthday. * Check our webpage BirthdayDroid Webpage * Open source: This project is an opensource project and you will find it at: Gitlab * Help us to have this app translated to your language If you want to help us to translate this app to your language go to: Transifex * Thanks to: App Icon: Firefox OS Emojis Navigation bar icons: Google Team Emojis: Free emojis provided by Emoji One * PERMISSIONS: * Read your contacts BirthdayDroid will work checking the birthday entry from each contact from your contact list so it will request you to have access to your contacts. You can check our source code if you still don't trust giving us that permission. * Control vibration Birthday Notifications * Run at Startup To register the time for the Birthday Notifications
F-Droid
Birthday Adapter
APK
Description Birthday Adapter provides birthdays, anniversaries, and other events from your contacts to the Android calendar system, which is displayed in your standard Android calendar application. To my knowledge, this is the first implementation that implements birthdays as a calendar displayed in Android's Calendar app. All other apps only displays their own lists but have no real integration! Features • Total integration of birthdays, anniversaries, and other events from Android's contacts to the Android calendar system • Color picker for the birthday calendar • Event Reminders • Jubilee markers • Filter contact events based on account and contact groups • Customize all event titles • Chose which events will have reminders Problems If you have problems with this app, please report them on the following website: https://github.com/SufficientlySecure/birthday-calendar/issues Translations Help translating Birthday Adapter on https://hosted.weblate.org/engage/birthday-adapter/ Source code and information https://github.com/SufficientlySecure/birthday-calendar License GPLv3 Keywords birthday calendar, birthday adapter, calendar integration, birthdays, events, special dates Open source alternative to EboBirthday, Birthdays, TKBirthdayReminder, Birthday Widget
F-DroidGitHub
Birthday Calendar
APK
Get a birthday calendar for all your social networks right inside Google Calendar. Supports Facebook, LinkedIn, Xing, Skype and all other apps which sync contacts with your Android device. Enable reminder alarms and decide which contacts you want to see. You'll get notifications for all of them. Features: * Birthdays and anniversaries for all your contacts * Customizable reminders (same day, one day in advance, ...) and the calendar color * Hide the app icon after setting it up so that it doesn't get in your way * Tablet support Based on https://f-droid.org/packages/org.birthdayadapter.
F-DroidGitHub
Birthday Countdown
APK
Birthday Countdown is a Free and Open Source App for Android Phones counting down to your next birthday. Can't await your next birthday? Me neither! So I built this Countdown App for you ^^ ~ Kim <33 Features Customizable birth dateCountdown to next birthdayMilestones on the way to next birthday
F-Droid
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