Calendar

284 open source Calendar apps

HIIT Timer
APK
Simple timer for high intensity trainings.
F-Droid
H
HOPE_16
APK
Program app for the HOPE_16 conference (2025) https://hope.net H.O.P.E. stands for Hackers On Planet Earth, one of the most creative and diverse hacker events in the world. It's been happening since 1994. Thousands of people from around the world come to HOPE. Join us for three full days and nights of activities, including provocative and enlightening speakers that the HOPE conferences are known for. The conference is in-person on the St. John's University campus in Queens, New York City. Many sessions will also be available online. Past HOPE events have featured fascinating talks, inspirational keynotes, and workshops on every topic from lockpicking to getting a ham radio license to analyzing Android malware. HOPE has showcased new movies, had cool live performances, done live radio broadcasts, and much, much more. Past speakers include Steve Wozniak, Jello Biafra, and Edward Snowden. 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 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) * Integration with the Engelsystem project https://engelsystem.de - Online tool for coordinating helpers and shifts on large events 🔤 Supported languages (Session descriptions excluded) * Danish * Dutch * English * Finnish * French * German * Italian * Japanese * Lithuanian * Polish * Portuguese (Brazil) * Portuguese (Portugal) * Russian * Spanish * Swedish * Turkish 💡 Questions regarding the content can only be answered by the HOPE conference content team. 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 in the issue tracker at https://github.com/EventFahrplan/EventFahrplan/issues. 🏆 The app is based on the EventFahrplan app which was initially built for the camp and annual congress of the Chaos Computer Club. The source code of the app is publicly available on GitHub at: https://github.com/johnjohndoe/CampFahrplan/tree/hope-2025. 🎨 HOPE owl artwork by Stefan Malenski.
F-DroidGitHub
HRLY
APK
HRLY (Hourly) is a minimalist hourly chime app designed to help you keep track of time without constantly checking your phone. It uses a simple system of long and short tones to signify the hour, running quietly in the background. ✨ Features - Simple Time System: Easily learn the time-telling system. - Customizable Sounds: Use your own audio files for both the short and long tones. - Notification Controls: Skip the next chime or stop the service directly from the notification. - Background Service: Runs efficiently in the background to chime on the hour. - Optional Visual Pulse: An optional visual pulse can accompany the chime on the lock screen. (Still working out some kinks) - User Control: Easily enable or disable the main chime service, visuals, and custom sounds. - Minimalist Design: A clean, no-frills interface. - Open Source: A "View Source" button provides a quick link to the project's GitHub page.
F-DroidGitHub
H
Halachic Prayer Times
APK
List of halachic/halakhic times for Jewish prayers (zmanim and zmanei tefillot). It also has a prayer compass, time opinions, and reminders. Times are calculated based on your location. An Internet connection is used to fetch your nearest address, otherwise the nearest country or time zone is used. Note: v6.0 is the last version available on F-Droid. Newer versions no longer meet our inclusion criteria and thus cannot be build. For details, please see https://gitlab.com/fdroid/fdroiddata/issues/839
F-DroidGitHub
Hey! Meditation
APK
Simple guide for short meditation sessions.
F-DroidGitHub
Holidayz
APK
# Holidayz App 📅 Stay Ahead with Global Public Holidays & Regional Days Off! 🎉 Looking for a simple and reliable way to check public holidays worldwide? 🌍 Public Holidays Calendar provides a complete overview of national and regional holidays for 100+ countries, all in an easy-to-use calendar format. ### Key Features: - ✅ View public holidays for over 100 countries - ✅ Check regional holidays for specific areas - ✅ User-friendly calendar layout for quick browsing - ✅ Plan ahead with accurate holiday information - ✅ Stay updated with yearly holiday schedules Whether you're planning a vacation, managing work schedules, or just staying informed, this app helps you keep track of important holidays worldwide. Download now and never miss a holiday again! 🎊🎈
F-DroidGitHub
Hourglass
APK
A simple application that can be used to start a timer from one second to one hour. The app can then be closed or left open, while a status bar notification reminds you that you have a timer in progress. Upon reaching 00:00, an audible bell as well as a short vibration and visual pop-up will indicate that your timer has ended. Great for reminding yourself to do something, or for use while playing games that require timers!
F-Droid
Hypezig
APK
What's happening in Leipzig? No matter if concert, cinema, lecture or sports event. You can now have all the events on your mobile phone. HYPEZIG loads information from existing event calendars from the internet. Decide for yourself which calendars you want to integrate. You can choose from: - kreuzer-leipzig.de - prinz.de/leipzig - sachsenpunk.de - the Facebook page "Sound of Leipzig - trichter.cc - Frauenkultur Leipzig - PLANLOS Leipzig - any iCal calendar (.ics file) - any Facebook page - more in the future Find events by their name, category or location. Mark events as favorites and receive a reminder one week and one day before. HYPEZIG is open source software. You can help shape the further development of the app. For more information, visit GitLab at https://gitlab.com/intergalacticsuperhero/hypezig Have fun!
F-Droid
ICSx⁵
APK
ICSx⁵ allows you to add/subscribe and manage external (Webcal) and local (i.e. Dropbox, adb push etc) iCalendar/.ics files on your Android device. Add high days and holidays, your sports teams events, time tables of your school/university or any other event files that come in ics/ical format. The app will import these events for you and displays it in your favorite calendar app on your Android – it integrates seamlessly into your device. * Subscribe to Webcal feeds (= synchronize at regular intervals) e.g. shared calendars from icloud.com * Subscribe to local .ics (iCalendar) calendar files * Allows to open webcal:// and webcals:// URLs, e.g. from your Web browser * Seamless integration to other calendar apps * Set a sync schedule * Intelligent update checker to save bandwidth * Authentication and HTTPS supported
F-DroidGitHub
Inner Breeze
APK
Find serenity in every breath with Inner Breeze. This app guides you through the Wim Hof Breathing Method with ease. Experience mindful breathing with personalized settings and track your journey towards tranquility and rejuvenation. This easy yet potent breathing technique promises profound inner peace, offering a sanctuary of serenity amidst life's hectic pace. Simply follow 4 steps: Inhale and exhale rhythmically for 30 breaths. Exhale and hold your breath. Inhale deeply and hold for 15 seconds. Exhale and repeat step 1. Do 3-10 rounds of the process.
F-DroidGitHub
Interval Timer
APK
An interval timer designed for HIIT workouts. Set your active and rest time, and hit go. Simple and easy-to-use.
F-DroidGitHub
J
JEV 2022 Schedule
APK
Conference program app for the JahresEndVeranstaltungen (JEV) https://events.ccc.de/2022/11/28/dezentral-2022/#dezentral-2022-events There will be no Congress and no centrally organised rC3 this year. This is a challenge that the community was happy to accept. Various groups are organising decentralised events with talks, workshops and other things in the usual Congress season. Parts of these events can be visited in person and other parts can be followed online. We have prepared an overview of all these events, sorted by (physical) location. All broadcasts will be viewable on media.ccc.de live and as recordings later. Please remember that the individual groups are organising these events autonomously and are individually responsible for their own content. 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 events * Add events to favorites list * Export favorites list * Setup alarms for individual events * Add events to your personal calendar * Share a website link to an event with others * Keep track of program changes * Automatic program updates (configurable in settings) * Vote and leave comments on talks and workshops * Integration with the Engelsystem project https://engelsystem.de - Online tool for coordinating helpers and shifts on large events * Integration with the Chaosflix https://github.com/NiciDieNase/chaosflix - Android app for https://media.ccc.de, share Fahrplan favorites with Chaosflix to import them as bookmarks 🔤 Supported languages (Event descriptions excluded) * Dutch * English * French * German * Italian * Japanese * Polish * Portuguese * Russian * Spanish * Swedish 💡 Questions regarding the content can only be answered by the content teams of the individual events. This app simply offers a way to consume and personalize the aggregated schedule of all the events. 💣 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
F-DroidGitHub
Just 24 Hours
APK
When all you need is to know what time it is, only the actual time matters. There are many wonderful clock applications available for Android devices. Many have have lots of great features. Choice in applications is a good thing. When one wishes to choose a simple clock application that just displays the time of day in as large numbers as can fit on the screen's device, Just 24 Hours is here! '''Features:''' Just 24 Hours will display the time of day in 24 hour format in a big numbers as will fit on the screen. For those that were corrective lenses, it can be challenging to read small numbers when just waking up. Big numbers are required. No matter what size screen your Android device has, Just 24 Hours will use as big a text size that will fit on the screen. That is all. No alarm settings. No typeface settings. No colour settings. Just a big clock to see what time of day it is. Of course, this is not what everyone wants in a clock application. This is okay. There are dozens of clock applications available for Android. Most (maybe all!) are great applications. We are certain that there will be one that will satisfy one's desired features. For those that just want the time, Just 24 Hours is here!
F-Droid
Karui ToDo
APK
An open source, privacy focussed, todo list app to quickly jot down things to do. Inspired by the system-24 theme and the Windows Mobile design system, this app's design is set to evolve into something even more eye-catching. Features - Simple note taking and list making: Includes an undo delete feature. - Retro terminalesque design: Inspired by Unix customizations found online. - Lightweight: Consumes only 0.05% CPU and 128KB of RAM. After all, simple apps shouldn't need more—remember, the Apollo mission operated on a computer with around 4KB of RAM! - Highly customizable: Offers many themes with plans to add more customizations such as fonts, font sizes, and border colors. - To add a new note tab: use the `///TabName` format. - To remove any tab (except the Main tab): use the `\\\TabName` format. For more details on features, usage, customizations, discussions, visit the github repo.
F-DroidGitHubIzzyOnDroid
KashCal
APK
All your calendars. One app. Your calendars are everywhere. Family stuff on iCloud. Holidays from some website. Birthdays buried in your contacts. Work on Nextcloud. KashCal brings them together on your Android. Your schedule, together • iCloud: Switched to Android but your family is still on Apple? Sync with iCloud calendars directly. No workaround needed. • CalDAV: Nextcloud, Radicale, Baïkal, Stalwart, FastMail, Zoho, and more. Native sync, no middleware. • Device calendar: See events from your phone's built-in calendar alongside everything else. • Holidays & schedules: Subscribe to any ICS calendar. Holidays, school schedules, sports seasons. • Birthdays: Pulls from your contacts automatically. • Local: Don't need sync? Works fully offline out of the box. Material You with dynamic theming. Home screen widgets. Full-text search across all events. Per-event timezone for travel. Private by default No analytics. No telemetry. No KashCal account. Your data stays on your device unless you set up sync yourself. • Encrypted credentials (AES-256-GCM) • Fort Knox Mode: other apps can't read your events • HTTPS only, no WebViews, minimal permissions • Open source: fully auditable Website: https://kashcal.github.io Source code: https://github.com/KashCal/KashCal
F-DroidGitHubIzzyOnDroid
Kimai TimeTracker
APK
Client for the time managment software Kimai. This app makes mobile tracking and logging into your kimai existing installation easier. If you want to be auto logged in after application start check the appropiate box. Normally you have to open your browser, go to favourites, click your kimai page, input data. Now you only have to do the last step every time you want to add entries.
F-DroidGitHub
Kitchen Timer
APK
Three independent timers on one screen.
F-Droid
L
LibreOffice 2024 Schedule
APK
Program app for the LibreOffice Conference 2024 https://conference.libreoffice.org About the LibreOffice Conference The LibreOffice Conference is the annual gathering of the worldwide LibreOffice Community and interested developers, marketers, adopters, end-users, and supporters. Our program reflects the broad engagement and diversity of the community: it includes talks and workshops from various areas of the project. 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 events * Add events to favorites list * Export favorites list * Setup alarms for individual events * Add events to your personal calendar * Share a website link to an event with others * Keep track of program changes * Automatic program updates (configurable in settings) 🔤 Supported languages (Event descriptions excluded) * Danish * Dutch * English * Finnish * French * German * Italian * Japanese * Lithuanian * Polish * Portuguese (Brazil) * Portuguese (Portugal) * Russian * Spanish * Swedish * Turkish 🤝 You can help to translate the app at: https://crowdin.com/project/eventfahrplan 💡 Questions regarding the content can only be answered by the LibreOffice Conference content team. 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 in the issue tracker at https://github.com/EventFahrplan/EventFahrplan/issues. 🏆 The app is based on the EventFahrplan app which was initially built for the camp and annual congress of the Chaos Computer Club. The source code of the app is publicly available on GitHub at: https://github.com/johnjohndoe/CampFahrplan/tree/libreoffice-2024. 🎨 LibreOffice Logo Design by Italo Vignoli.
F-DroidGitHub
LifeDots - Diary in 8 dimensions
APK
LifeDots is for recording and analysing your life with ease in the 8 dimensions of time, event, location, notes and photo. Currently you can record any event by touching on an icon that you create, entering notes and attaching photos. Locations are automatically recorded (after you activate) in the background. Then you can browse your history, analyze statistics in charts, check the timeline of any event, and see your past geo locations. Further more, for easier viewing life from various perspectives, these analytic functionalities are interconnected: check timeline on any pieve of a piechart, review related history about a dot on the timeline, look at geographical passages related to a period of history, and go back to related history on a dot on the map. LifeDots is a free and open-source software. There is no advertising and no requirement for purchase of kind. All of your data remain on your own device. Internet connection is only needed for dynamically downloading the necessary and free map tiles when you need.
F-DroidGitHub
LightPlan - Reminder & Planner
APK
Light Planner is a FOSS, simple, and intuitive app that will help you with planning events, tasks, or achievements you want to reach! ============== How does it work? ============== • Add your tasks in a chosen year quarter • Write up a title and a description and pick a deadline for it That’s it! Upon entering the task area, you will be shown the time you have left to complete it and (optionally) the subtasks you have created in it. ============== Who is it made for? ============== Anyone! No matter the age or height, you can use the app to plan ahead and keep track of the time you have left to complete it at any time. ============== How is it different from other apps? ============== This app was designed to be simple and intuitive, while still looking slick and unintrusive. We also don’t collect any data from users (everything is stored on your device), which means you don’t have to create/link an account and you won’t have to deal with any pesky ads! Additionally, the project is open-source, so if you feel like changing or adding features, you can do it! (link to the project repository: https://github.com/XDDK/LightPlan). I hope you'll find this app useful!
F-DroidGitHub
LinCal
APK
"LinCal" is short for "Link Calendar" and allows to show links or small messages at predefined points in time, in the form of notifications. If the message is a link, it can be opened by clicking the notification. Calendars are created as a text file using a simple format and can then be loaded into the app. Use it as Advent calendar or just to make someone happy!
F-DroidGitHub
Linwood Flow Nightly
APK
Linwood Flow is a free, opensource time and event management software. You can choose where your data is stored and who can access it. Group your events and manage places and people. The app is available for Windows, Linux, Android and Web. * Simple and intuitive: Every tool is in the right place. Open the app and start managing your time. Invite people to your events and share your calendar with them. * Support your favorite formats: Import and export your old notes and events. Set the app as your default calendar app and use it with your favorite apps. * Works on every device: The app is available for android, windows, linux, and in the web. You can use it on your phone, tablet, or computer. * Choose where your data is stored: You can choose to store your data locally, in your favorite cloud (caldav) or decentralized using S5. You can also export your data to a file and import it again. * Available in many languages: The app is available in many languages. Help us to translate this app to your language. * FOSS: The app is open source and free. You can contribute to the project and help to make it better. * Use it offline: You can use the app offline. You can draw, paint, and export your notes without an internet connection. * Manage your time: You can manage your time using a calendar. You can add events to it and share them with your friends. * Manage your places: You can add places to the app and share them with your friends. Keep track which places are free and which are busy. * Manage users: Add users to the app to keep track of who is available and who is not. You can also share your calendar with them. Add birthdays to the app and get a notification when it is time to celebrate. * Manage your tasks: You can add tasks to the app and share them with your friends. You can also add your favorite tasks to the app. Set a deadline and get notified when it is due. * Take notes: You can add files and notes to your events. Add a backlog to your events to keep track of your progress. * Group your events: Group your events to know which events are related to each other. You can also add tags to your events to find them faster. * Irregular events: You can add irregular events to the app. Have irregular meetings? Add them to the app and get notified when it is time to meet. Simply copy the event and change the date.
F-DroidGitHub
Lux Alarm
APK
Stop Oversleeping with Lux Alarm Tired of hitting snooze and waking up late? Lux Alarm ensures you actually get out of bed by requiring light to silence the alarm. How it works To stop the alarm, you must get up and open your blinds or turn on the light. The app uses your phone's sensor to detect brightness; by the time the alarm turns off, you are already on your feet and ready to start your day. Key Features • Smart Light Detection: Uses your phone's sensor to ensure the alarm only deactivates once your environment is bright. • Adjustable Sensitivity: Customize the required light level to account for gloomy weather or different room setups. • Modern Interface: A clean, intuitive design based on Material Design 3 for easy navigation. • Circadian Support: Waking up with light helps regulate your natural sleep cycle and reduces morning grogginess.
F-DroidGitHub
M
MRMCD 2025 Schedule
APK
Programm zur 📂 MRMCD 📂 Konferenz 🔍 https://2025.mrmcd.net Funktionen * Tagesüberblick über alle Programmpunkte * Beschreibung von Veranstaltungen lesen * Veranstaltungen in persönlicher Favoritenliste verwalten * Alle Veranstaltungen durchsuchen * Favoritenliste exportieren * Alarm für Veranstaltungen setzen * Veranstaltungen in Kalender eintragen * Link zu Veranstaltungen mit anderen teilen * Programmänderungen einsehen * Veranstaltungen bewerten * Integration mit dem Engelsystem-Projekt https://engel.mrmcd.net - Online-Tool für Helfer- und Schichtplanung auf großen Events * Integration mit Chaosflix https://github.com/NiciDieNase/chaosflix - Android App für https://media.ccc.de, teile Fahrplan-Favoriten mit Chaosflix und importiere sie als Bookmarks (RIP NiciDieNase) 🔤 Unterstützte Sprachen (Programmtexte ausgenommen) * Dänisch * Deutsch * Englisch * Finnisch * Französisch * Italienisch * Japanisch * Litauisch * Niederländisch * Polnisch * Portugiesisch, Brasilien * Portugiesisch, Portugal * Russisch * Spanisch * Schwedisch * Türkisch 💡 Inhaltliche Fragen zum Programm kann nur das MRMCD-Team beantworten. Diese App stellt lediglich die Programmpunkte zur Verfügung. 💣 Fehlerberichte sind herzlich willkommen, aber achte darauf, dass du erklärst, wie man den Fehler reproduzieren kann. Der Issue-Tracker findet sich hier: https://github.com/EventFahrplan/EventFahrplan/issues 🏆 Die App basiert auf der EventFahrplan-App https://f-droid.org/packages/info.metadude.android.congress.schedule/ für den Kongress des Chaos Computer Clubs. Der Quellcode der Anwendung ist auf GitHub https://github.com/johnjohndoe/CampFahrplan/tree/mrmcd-2025 zu finden. 🎨 MRMCD-Design von Leif Niemczik, https://leifs.website
F-DroidGitHub