Calendar

284 open source Calendar apps

PlugBrain
APK
PlugBrain is an app that encourages regular breaks from distracting apps by blocking access at scheduled intervals. To regain access, you’ll need to solve a math challenge that adjusts in difficulty: the more frequently you use the apps, the harder the challenges become, but the longer you stay away, the easier they get. **Features** - No ads - No internet required - Blocks distracting apps - Unblock apps by solving math challenges - Difficulty increases with frequent use, decreases with focus **How to use** - Grant all required permissions - Select distracting apps - Choose your focus interval - Stay focused ;)
F-DroidGitHubIzzyOnDroid
PocketCheck
APK
You forget to return things to their proper place after using them. You accidentally take home things you borrowed. You leave tasks half-done. And worst of all — you forget to even check your checklist. PocketCheck is a working memory app for people like you. The app periodically asks "Anything to put in your pocket?" You don't have to remember to check yourself. FEATURES Item Management • Register items with name and notes • Quick photo registration - snap a photo to register instantly • Switch toggle to manage task status • Visual distinction for active tasks • Swipe left to delete, swipe right to archive • Drag & drop to reorder items Smart Reminders • Periodic notifications: "Anything to put in your pocket?" • Tap "Yes" to open app, "No" to dismiss • Notifications don't pile up - stays as one • Configurable interval and quiet hours Persistent Status • Always-visible notification when tasks are active • Silent, non-dismissible notification • Shows active tasks Privacy First • Works completely offline • No accounts, no tracking • No Google Services required • Your data stays on your device • Open source (GPL-3.0)
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Polar Clock
APK
A polar clock, inspired by the one made by pixelmaker:
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Polite Droid
APK
Activates silent mode during calendar events.
F-DroidGitHub
PolyCal
APK
The color coding is intended to be especially useful for people who must coordinate multiple calendars. Multiple widgets can be added, and they will have separate calendar selection settings. It is relatively simple, at least by Android project standards, and attempts to use the standard practices for each part. By default, it has no calendar permissions, and so it will be in "screenshot mode" (which was also used to prepare the app widget preview). Source Code (GPLv2): https://github.com/jasongyorog/PolyCal Privacy Policy: http://gyorog.com/PolyCal-privacy.html
F-DroidGitHub
Pomodoro
APK
This is a very simple and tiny pomodoro timer app for Android 2.3 and later, with support for WearOS devices too!Features:Countdown & countup timer (up to 96 hours)Cyan flashing and/or alarm sounds reminder when each pomodori completedNormal texts or text arts displayControls:Single tap: Pause & resume active timer, Dismiss flashing reminderDouble tap: Stop active timerLong tap: Set a new timerSwiping: Switch between text art fonts
IzzyOnDroid
Pomozen
APK
Pomozen is a modern, open-source Pomodoro timer app designed to boost productivity and focus. It applies the Pomodoro Technique—structuring work into focused intervals (typically 25 minutes) followed by short breaks. This systematic approach helps combat mental fatigue, maintain concentration, and improve efficiency in work or study.Key Features:📊 Comprehensive Statistics: Track focus sessions, break times, and productivity patterns. Custom labels let you track time spent on specific tasks, activities, or anything you want.⏰ Customizable Reminders: Stay on track with personalized notifications. Smoothly transition between focus and break periods.💧 Hydration Reminder: Get timely reminders to drink water and stay hydrated throughout your day.🧘 Minimal Design: Clean, focused interface built with minimalism at its core—balanced spacing, calm colors, and no distractions.📴 Offline Support: No internet? No problem. All features, timers, and logs work offline.⚙️ Fully Customizable Timer: While the default Pomodoro cycle is 25/5/15, you can fine-tune focus time, short/long breaks, session count, and reminder behavior to match your personal workflow.Privacy FirstPomozen has a strict no data collection policy. All session logs and preferences are stored only on your device—never sent to external servers or third parties.
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Počasí v krajích
APK
A short-term forecast for the regions of Czech Republic. Available only in Czech language.
F-Droid
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Prayer Time Muter
APK
Prayer Time Muter automatically silences your device around prayer times. Features: - Diyanet-compatible prayer times - Per-prayer mute offsets - Friday noon custom offsets - Silent or silent+vibrate modes - Offline cache support
F-DroidGitHub
Prayer mode
APK
Are you tired of remembering to silence your phone before every prayer? Have you ever been interrupted by notifications during Salah or worried about disturbing others? Prayer Mode solves this by automatically activating Do Not Disturb mode at precise prayer times, allowing you to focus completely on worship without distractions. 🎯 Set It Once, It Works Automatically: • Smart Automation: Activates DND mode at exact prayer times • 23 Calculation Methods: Choose from established prayer time calculations (aladhan.com API) • Location-Aware: Automatically adjusts when you travel • Complete Customization: Individual settings for every prayer scenario 🕌 Prayer-Specific Features: • Five Daily Prayers: Custom silent durations for Fajr, Dhuhr, Asr, Maghrib, Isha • Friday Prayer: Silent periods before and after Adhan • Ramadan Nights: Settings for Taraweeh and Tahajjud • Eid Prayers: Custom timing for Eid al-Fitr and Eid al-Adha • Audio Takbir: Optional sound notification before silence • Ablution Time: DND 10 minutes before Adhan for preparation 🔔 Stay Informed: • Notifications for DND activation/deactivation • Prayer time updates when travelling • Reminders for Fajr, Friday Dhuhr, and Ramadan Imsak ✨ User Experience: • Clean interface with Light/Dark themes • Quick Settings Tile for instant access • Multi-language support (Arabic, English, French, Urdu, Indonesian, Malaysian, Turkish, Bengali, Spanish + more coming) • Privacy First: No data collection - all processing happens on your device 🌍 Serving the Muslim Ummah: We're committed to providing a respectful, accurate tool for prayer focus. Expect regular free updates with new features and improvements. Download Prayer Mode today and experience uninterrupted, focused prayer.
F-DroidGitHub
Presentation Timer
APK
Simple timer for presentations. It rings bell at specified time. You can specify up to three bell timing. You can ring bell manually, too. When bell rings, the timer text color will be changed.
F-DroidGitHub
ProgressBars
APK
Countdown/up to/from a specified time * Percentage complete for a time interval * Notifications on timer completion * Swipe to delete timers * Drag to reorder timers * Show time remaining / elapsed in any combination of, Years, Months, Weeks, Days, Hours, Minutes, or Seconds
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Protocol Berg Schedule
APK
The decentralized protocol and infrastructure conference. Protocol Berg v2 is a conference focusing on protocol research, decentralized infrastructure, and core-developer experience. The two-day event with multiple stages, opportunities for technical workshops, and protocol community gatherings brings together protocol researchers and other stakeholders from different decentralized protocols. Attendance is free of charge. The event will not host any sponsors or commercial talks. https://protocol.berlin 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 * Search through all 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 🔤 Supported languages (Event 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 Protocol Berg 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. The issue tracker can be found here: https://github.com/EventFahrplan/EventFahrplan/issues 🎨 Protocol Berg v2 logo: CC BY-NC-SA 4.0 Department of Decentralization
F-DroidGitHub
Proton Calendar
APK
Secure, encrypted calendar for your Android devices.
Direct
QRAlarm
APK
Say goodbye to oversleeping with QRAlarm! 🚀 QRAlarm - QR Code Alarm Clock is an effective and smart alarm clock that gets you out of bed by making you scan the QR or Barcode to turn off the alarm! This makes it perfect for both heavy sleepers and productive early risers! 🔝 Have you ever... - ⏰ ...found yourself caught in the “snooze loop” where you kept snoozing the alarm while never getting up? - 😴 ...turned off your alarm giving yourself those mythical “5 more minutes” just to fall back asleep again and oversleep? - 📝 ...wanted to start off the day earlier to get your tasks done but you simply couldn’t leave your bed in the morning? Then QRAlarm is perfect for you! 🫵 QRAlarm is not just another alarm clock app - the QR alarm mission functionality is there to help you always get up on time! Because a strong and innovative alarm clock does not only wake you up - it makes sure that you GET UP! 🙌 If you are seeking to: - Fight with oversleeping, - Break your snooze habits, - Improve your morning productivity, - Build your perfect morning routine, - Stay healthy and happy, Then you have found the perfect alarm clock application - this is your new life hack! 📈 QRAlarm is a simple and lightweight alarm clock! Don't worry about low memory in your phone - QRAlarm is only around 15 MB making it perfect fit for everyone, no matter the device! 📱 QRAlarm has a simple, clean and intuitive user interface that makes the experience easy and seamless! You will feel at ease using QRAlarm as it does not overwhelm the user with bloated functions. QRAlarm is uncluttered, clear and beautiful! ✨ Download the app now, set up and configure your alarms and let QRAlarm work its magic! 🪄
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Qadaa
APK
- Easy and simple interface. - Password for application - Sound and visual effects when spending a prayer or day - Motivated notifications when spending every day. - Dark mode of application. - Two modes of the first screen either photo or static color. - Direct pressure on the facade elements to spend the thing about it. - Determining the number of prayers a day. - Letter showing you the expiration date based on the number of prayers and the number of judges per day.
F-DroidGitHubIzzyOnDroid
QueueToDo
APK
Task management app. The queue instead of a task list to force execution order. Lightweight and simple.
F-Droid
Quick Timer
APK
Quick Timer Tile makes managing your time effortless and distraction-free.Add it to your Quick Settings, and you’re ready to go – no app icon or traditional interface. Everything happens through a timer dialog and notification.How to get started:Add the Timer to Quick Settings:Swipe down from the top of your screen to open Quick Settings.Tap the pencil icon or "Edit" to customize your tiles.Drag the "Timer" tile into the active area.Set up your timer:Tap the "Timer" tile to open the timer setup dialog.Grant notifications permission (if needed).Use the pickers to set the desired time and press "Start".Follow the Timer in Notifications:Once the timer starts, a notification shows the remaining time.Pause, resume, or cancel the timer directly from the notification with one tap.Why use Quick Timer?Quick access: start a timer in seconds straight from Quick Settings.No clutter: no app screen or icon – just a clean, efficient experience.Convenient notification: always know how much time is left at a glance.Perfect for cooking, workouts, or any activity where timing matters!
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Radicale
Web
Lightweight CalDAV and CardDAV server for self-hosting calendars and contacts.
React
APK
Allows you to test your reaction time.
F-DroidGitHub
R
Record Time Droid
APK
RecordTimeDroid records time and shows elapsed time between previously recorded lines. It is useful to people who want to measure times for different tasks. It also is good for people who want to record date and time to store later.
F-Droid
Red Dot
APK
This parametric animation, under the current technology, is 49 years long, Starting 1970 January 1, it is not random, is synchronized over all devices and ideally never repeat itself. The Red Dot is just a symbol, a representation of something else. Take a look and find your our own meaning for it.
F-DroidGitHub
Remind Me
APK
A minimalistic app for quick reminders.Features:Set reminders within the next 24 hoursClear list of all pending remindersSwipe-to-delete individual remindersDelete all with confirmationMinimalistic designFully open sourceNo trackers, no analyticsPerfect for short memory aids in everyday life.
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Remindly
APK
Add reminders to the notification list.
F-DroidGitHub