Open Source Calendar Software
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Calendar Software
View 122 business solutionsBrowse free open source Calendar software and projects below. Use the toggles on the left to filter open source Calendar software by OS, license, language, programming language, and project status.
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Outlook CalDav Synchronizer
Sync Outlook with Google, SOGo or any other CalDAV / CardDAV server
Free Outlook Plugin, which synchronizes events, tasks and contacts between Outlook and Google, SOGo, NextCloud, Horde or any other CalDAV or CardDAV server. Supported Outlook versions are 2021, 2019, 2016, 2013, 2010 and 2007 and Office 365 for Desktop. This project was initially developed as a master thesis project at the University of Applied Sciences Technikum Wien, Software Engineering Degree program. Outlook CalDav Synchronizer is Free and Open-Source Software (FOSS), still you can support the project by donating on Sourceforge or directly within the About dialog of our Plugin. Contact us for enterprise support at https://caldavsynchronizer.org/enterprise/contact -
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Vtiger CRM
An enterprise-class CRM and more!
Vtiger CRM enables sales, support, and marketing teams to organize and collaborate to measurably improve customer experiences and business outcomes. Vtiger CRM also includes email, inventory, project management, and other tools, providing a complete the business management suite. Download Vtiger CRM here or sign up for a free 15-day free trial of the cloud-based application with free updates and support at https://www.vtiger.com/ -
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DavMail is a POP/IMAP/SMTP/CalDAV/CardDAV/LDAP Exchange and Office 365 gateway allowing users to use any mail/calendar client (e.g. Thunderbird with Lightning or Apple iCal) with an Exchange server. DavMail now includes an LDAP gateway to Exchange global address book and user personal contacts to allow recipient address completion in the mail compose window and full calendar support with attendee free busy display. The main goal of DavMail is to provide standard compliant protocols in front of proprietary Exchange. This means LDAP for address book search, SMTP to send messages, IMAP to browse messages on the server in any folder, POP to retrieve inbox messages only, CalDAV for calendar support and CardDAV for contact synchronization.
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!!We've Moved to GitHub at http://github.com/libical !!The code here on SourceForge is frozen !!Please follow us at http://libical.github.io/libical The Free Association project maintains libical, an open source reference implementation of the icalendar data type and serialization format. libical is used in dozens of calendaring and scheduling products.
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Build Agents and Models on One PlatformGemini Enterprise Agent Platform is Google Cloud's comprehensive platform for developers to build, scale, govern, and optimize agents and models. Choose from Google's most advanced models and third-party models like Anthropic's Claude Model Family.
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FullCalendar
Full-sized drag & drop event calendar
FullCalendar generates real React virtual DOM nodes so you can leverage Fiber, React's highly optimized rendering engine. With over 300 settings, and more being added every release, FullCalendar can do just about anything. Reduce your project's bundle size by using FullCalendar's modular plugins. With over 10 years of open source and over 100 contributors, FullCalendar will always have a free and open source core. Level-up by purchasing premium plugins and support. FullCalendar seamlessly integrates with the React JavaScript framework. It provides a component that exactly matches the functionality of FullCalendar’s standard API. This is more than a mere “connector”. It tells the core FullCalendar package to begin rendering with React virtual DOM nodes as opposed to the Preact nodes it normally uses, transforming FullCalendar into a “real” React component. You can learn a bit more from this blog post (more info to come). -
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Cal.diy
Scheduling infrastructure for absolutely everyone
The Cal.diy project is a fully open-source, self-hosted scheduling platform that provides an alternative to proprietary booking tools while giving users complete control over their infrastructure. It is a community-driven fork of Cal.com that removes all enterprise and commercial features, ensuring that the entire codebase remains MIT-licensed and accessible. The platform enables users to manage bookings, availability, and integrations without relying on external services or subscription models. Built with modern web technologies such as Next.js, React, and PostgreSQL, it offers a robust foundation for building custom scheduling workflows. The system is designed for developers and advanced users who prefer to host and secure their own data rather than depend on third-party providers. It also supports integration with external tools through APIs and authentication systems, allowing flexible customization. -
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Group Office groupware and CRM
Take your office and CRM into the cloud!
Installation instructions can be found here: https://groupoffice.readthedocs.io/en/latest/install/install.html Group Office is an open source groupware application. It makes your daily office tasks easier. Share projects, calendars, files and e-mail online. It is a complete solution for all your online office needs. From a customer phone call to a project and finally an invoice. The support system helps to keep your customers happy. Group Office is fast, secure and has privacy by design. You can stay in full control of your data by self hosting your cloud and e-mail. Our document editing solution keeps all data on the secured server instead of synchronising it to all user devices. GroupOffice is open source and modular. Which means it’s easy to customise and extend. You can turn off and on features and it enables any developer to create new modules for the platform. -
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Etar Calendar
Android open source calendar
Etar is an open-source material-designed calendar made for everyone. -
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Outlook Google Calendar Sync
Sync your Outlook and Google calendars
Offers calendar synchronization between Outlook and Google, including attendees and reminders. Completely free, no install necessary, works behind web proxies and actively developed. Supports all versions of Outlook from 2003 to 2019/Microsoft365 64-bit! Installable and portable options - even runs from a USB thumbdrive. Synchronises items in any calendar folder, including those shared with you. Differential comparison updates only attributes that have changed. Customizable date range to synchronize, past and future. Frequency of automatic syncs, including push-sync from Outlook. Configurable proxy settings, or use Internet Explorer's. Merge new events into existing on the destination calendar. Prompt on deletion of items. Ability to obfuscate custom words for privacy/security. Option to force items as public or private in target calendar. Syncs recurring items properly as a series. -
MongoDB Atlas runs apps anywhereMongoDB Atlas gives you the freedom to build and run modern applications anywhere—across AWS, Azure, and Google Cloud. With global availability in over 115 regions, Atlas lets you deploy close to your users, meet compliance needs, and scale with confidence across any geography.
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Project has moved to github: https://github.com/craigk5n/webcalendar WebCalendar is a PHP application used to maintain a calendar for a single user or an intranet group of users. It can also be configured as an event calendar.
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RedNotebook is a graphical diary and journal helping you to keep track of notes and thoughts. It includes a calendar navigation, customizable templates for each day, export functionality and word clouds. You can also format, tag and search your entries. Please find the latest releases at https://rednotebook.app
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React Infinite Calendar
Infinite scrolling date-picker built with React
The React Infinite Calendar project is a highly customizable date picker component for React applications that leverages virtualized rendering to provide smooth infinite scrolling through dates. It is designed to handle large date ranges efficiently by rendering only visible elements, which significantly improves performance compared to traditional calendar components. The library supports features such as localization, theming, keyboard navigation, and flexible date constraints, making it suitable for a wide variety of use cases. It integrates seamlessly with modern React workflows and supports multiple module formats for easy adoption in different environments. The component also includes advanced display options such as overlays, animations, and helper elements to enhance user experience. Its architecture relies on virtualization techniques to maintain responsiveness even when navigating across decades of dates. -
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Cal.com
Scheduling infrastructure for absolutely everyone
Meet Cal.com, the event-juggling scheduler for everyone. Focus on meetings, not making meetings. Free for individuals. Cal reads your availability from all your existing calendars ensuring you never get double booked! Set repeating schedules for the times of the day and week that you want people to be able to book you. Share your short cal.com personal link and make it incredibly easy for people to book a meeting at a time that works for both of you! Set availability, location, duration and more on a per-link basis. Send bookings to different calendars or set a default. Cal.com checks for conflicts across all of your calendars and only offers times that are open. Never get double-booked again. Cal.com enables you to build processes around your events. Notifications, reminders, and follow-ups are automatically taken care of. -
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Simple Calendar
A simple calendar with events, customizable widgets and no ads
The most handy calendar out there. Manage your events and reminders easily. Simple Calendar Pro is a really flexible calendar with many event related options. It offers powerful repetition rules, optional CalDAV synchronization, ics file handling and much more. Top notch design ensures the best possible user experience. You will get familiar with it really quickly. You can create new events really quickly by predefining default values, or by duplicating existing events. There are many views you can choose from, depending on your preference. No matter if you want to see just 1 day or 1 year, this app supports it. Personalize your experience by changing any app color. You can even change the apps' icon color to make sure it matches your home screen. The Pro one already has many new features including time zone support, attendees and email type of reminders in CalDAV synced events, then many other bugfixes and stability improvements. -
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Osmo is a handy personal organizer, which includes calendar, tasks manager, address book and notes modules. It was designed to be a small, easy to use and good looking PIM tool to help to manage personal information.
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Joda-Time
Replacement for the Java date and time classes prior to Java SE 8
The standard date and time classes prior to Java SE 8 are poor. By tackling this problem head-on, Joda-Time became the de facto standard date and time library for Java prior to Java SE 8. Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project. The design allows for multiple calendar systems, while still providing a simple API. The “default” calendar is the ISO8601 standard which is used by many other standards. The Gregorian, Julian, Buddhist, Coptic, Ethiopic and Islamic calendar systems are also included. Supporting classes include time zone, duration, format and parsing. Joda-Time provides a quality replacement for the Java date and time classes. Joda-Time is the de facto standard date and time library for Java prior to Java SE 8. Users are now asked to migrate to java.time (JSR-310). -
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react-big-calendar
gcal/outlook like calendar component
An events calendar component built for React and made for modern browsers (read: IE10+) and uses flexbox over the classic tables-ception approach. Styles can be found at: react-big-calendar/lib/css/react-big-calendar.css, and should be included on the page with the calendar component. Also make sure that your calendar's container element has a height, or the calendar won't be visible. Date internationalization and localization is hard and react-big-calendar doesn't even attempt to solve that problem. Instead you can use one of the many excellent solutions already out there, via adapters called "localizers". Big Calendar comes with two localizers for use with Globalize.js or Moment.js. Choose the localizer that best suits your needs, or write your own. Whatever you do, you'll need to set it up before you can use the calendar (you only need to set it up once). -
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react-calendar
Ultimate calendar for your React app
React-Calendar is a customizable React component for selecting dates and navigating calendar periods. Users can choose individual days, months, years, or decades through progressively broader views. Range selection allows applications to capture both the beginning and end of a period. Multiple calendar systems are supported, including Gregorian, ISO 8601, Hebrew, and Islamic configurations. Localization relies on browser internationalization capabilities and works with virtually any language. Developers can control displayed periods, views, selectable ranges, values, and styling through component props. The package requires no Moment.js dependency and is designed to remain lightweight and easy to integrate into modern React applications. -
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CrunchyCalendar
A beautiful material calendar with endless scroll, range selection
A beautiful material calendar with endless scroll, range selection, and a lot more. A light, powerful and easy-to-use Calendar Widget with a number of box features. -
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Tempus Dominus
A date/time picker widget
Tempus Dominus is the successor to the very popular "eonasdan/bootstrap-datetimepicker". The plugin provide a robust date and time picker designed to integrate into your project. The picker uses the format option to decide what components to show. Set format to LT, LTS or another valid MomentJs format string to display certain components. The picker uses MomentJs to determine the language string. You can use moment-with-locales or you can include whatever local file you need. Start of the week is based on the locale provided. This is defined by moment's locales. If you want to change it, create your own locale file or override. Looking for a template with the datepicker ready to go? Then get check out the templates provided in our website. Bootstrap.js is needed (transition and collapse are required if you're not using the full Bootstrap). -
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morilog/jalali
This Package helps developers to easily work with Jalali
Jalali calendar is a solar calendar that was used in Persia, variants of which today are still in use in Iran as well as Afghanistan. Read more on Wikipedia or see Calendar Converter. Calendar conversion is based on the algorithm provided by Kazimierz M. Borkowski and has a very good performance. CalendarUtils class was ported from jalaali/jalaali-js. -
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Pendulum
Python datetimes made easy
Pendulum is a Python package to ease datetime's manipulation. It provides classes that are drop-in replacements for the native ones (they inherit from them). Special care has been taken to ensure timezones are handled correctly, and are based on the underlying tzinfo implementation. For example, all comparisons are done in UTC or in the timezone of the datetime being used. There are several different methods available to create a new DateTime instance. datetime() sets the time to 00:00:00 if it's not specified, and the timezone (the tz keyword argument) to UTC. Otherwise it can be a Timezone instance or simply a string timezone value. Pendulum gives access to more attributes and properties than the default datetime class. The __str__ magic method is defined to allow DateTime instances to be printed as a pretty date string when used in a string context. Simple comparison is offered up via the basic operators. -
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React Native Calendars
Customizable React-Native calendar components
This module includes various customizable React-Native calendar components. The package is both Android and iOS compatible. This project is compatible with Expo/CRNA (without ejecting), and the examples have been published on Expo. The solution is implemented in JavaScript so no native module linking is required. All parameters for components are optional. By default the month of current local date will be displayed. Parameters that require date types accept YYYY-MM-DD formatted date-strings, JavaScript date objects, calendar objects and UTC timestamps. Calendars can be localized by adding custom locales to LocaleConfig object. Keep in mind that different marking types are not compatible. You can use just one marking style for a calendar. If you need custom functionality not supported by current day component implementations you can pass your own custom day component to the calendar. -
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React-Date-Picker
A date picker for your React app
React-Date-Picker is a React component that combines editable date fields with a popup calendar interface. Users can enter dates manually or choose them visually through its integrated React-Calendar component. It supports selecting days, months, years, and broader periods depending on the configured detail level. Localization uses standard language tags and browser locale information without requiring Moment.js. Developers can define minimum and maximum dates, formatting rules, calendar behavior, placeholders, and custom icons. Accessibility options include dedicated labels for calendar controls, date fields, native input, and clearing actions. The component can be styled with its default CSS or customized to match an application's interface. -
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bootstrap-datepicker
A datepicker for twitter bootstrap
Bootstrap-datepicker provides a flexible datepicker widget in the Bootstrap style. Versions are incremented according to semver. As with bootstrap’s own plugins, datepicker provides a data-api that can be used to instantiate datepickers without the need for custom javascript. You can disable datepicker’s data-api in the same way as you would disable other bootstrap plugins. Most options can be provided via data-attributes. An option can be converted to a data-attribute by taking its name, replacing each uppercase letter with its lowercase equivalent preceded by a dash, and prepending “data-date-” to the result. Methods are called on a datepicker by calling the datepicker function with a string first argument, followed by any arguments the method takes.
