Calendar Software for Windows

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Browse free open source Calendar software and projects for Windows below. Use the toggles on the left to filter open source Calendar software by OS, license, language, programming language, and project status.

  • Rezku Point of Sale Icon
    Rezku Point of Sale

    Designed for Real-World Restaurant Operations

    Rezku is an all-inclusive ordering platform and management solution for all types of restaurant and bar concepts. You can now get a fully custom branded downloadable smartphone ordering app for your restaurant exclusively from Rezku.
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  • Melis Platform is an enterprise-grade Low Code Platform simplifying app creation, management, and delivery. Icon
    Melis Platform is an enterprise-grade Low Code Platform simplifying app creation, management, and delivery.

    Ideal for websites, apps, e-commerce, CRMs, and more

    Melis is a new generation of Content Management System and eCommerce platform to achieve and manage websites from a single web interface easy to use while offering the best of open source technology.
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  • 1
    DavMail POP/IMAP/SMTP/Caldav to Exchange
    Ever wanted to get rid of Outlook ? DavMail is a POP/IMAP/SMTP/Caldav/Carddav/LDAP gateway allowing users to use any mail client with Exchange and Office 365, even from the internet through Outlook Web Access on any platform, tested on MacOSX, Linux and Windows
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    Downloads: 939 This Week
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  • 2
    Vtiger CRM

    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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    Downloads: 638 This Week
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  • 3
    Outlook CalDav Synchronizer

    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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    Downloads: 427 This Week
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  • 4
    Group Office groupware and CRM

    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.
    Downloads: 75 This Week
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  • The Industry Leading Platform for eCommerce Enablement and Analytics Icon
    The Industry Leading Platform for eCommerce Enablement and Analytics

    With MikMak Insights, brands gain real-time eCommerce analytics on the channels, campaigns, creative, and audiences that drive conversions.

    MikMak’s Where to Buy Shoppable Solutions help multichannel brands drive sales, grow market share, and increase profitability while reducing costs across categories such as CPG, Grocery, Alcohol, Beauty, Personal Care, Pet Care, Home Care, Consumer Electronics, Home Appliances, Toys, and more.
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  • 5
    FullCalendar

    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).
    Downloads: 11 This Week
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  • 6
    Cal.com

    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.
    Downloads: 10 This Week
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  • 7
    Outlook Google Calendar Sync

    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.
    Downloads: 9 This Week
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  • 8
    bootstrap-datepicker

    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.
    Downloads: 9 This Week
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  • 9
    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
    Downloads: 26 This Week
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  • Streamline Hiring with Skill Assessments Icon
    Streamline Hiring with Skill Assessments

    Say goodbye to hiring guesswork. Use Canditech’s job simulation tests to assess real-world skills and make data-driven decisions.

    Canditech offers innovative, cheat-proof skill assessments and job simulations to transform your hiring process. From technical skills to soft skills, we help you assess candidates on actual job performance. With over 500 customizable tests and powerful video interview features, you can evaluate real-world capabilities, streamline your hiring, and reduce biases. Whether you’re hiring for remote roles, mass hiring, or looking to expand your diversity pool, Canditech’s data-driven platform ensures the right candidates are chosen for the job every time.
    Get a Free Demo
  • 10
    qOrganizer is a general organizer that includes a calendar with schedule,reminders,journal/notes for every day, to-do list.But provides features useful for students such as:timetable and a booklet for marks and absences.It's designed to be easy to use.
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    Downloads: 21 This Week
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  • 11
    IGSuite - Integrated Groupware Suite

    IGSuite - Integrated Groupware Suite

    IGSuite is a web-ajax-based Integrated Groupware Suite

    IGSuite is a web-based Integrated Groupware Suite oriented to be a CRM solution. In the Suite you can find: IGWebMail, IGCalendar, IGContacts, IGArchive, IGWiki, IGTodo, IGChat, Projects, IGFax an HylaFax client, IGFileManager, IGMsg and many other.
    Downloads: 43 This Week
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  • 12
    WebCalendar
    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.
    Downloads: 22 This Week
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  • 13
    Zentyal, Linux Small Business Server

    Zentyal, Linux Small Business Server

    Zentyal is a Linux Small Business Server

    Zentyal Server is an easy to use and affordable Linux server, specially designed to meet the needs of small and medium businesses Thanks to Zentyal's Samba integration, Zentyal provides native compatibility with Microsoft Active Directory, allowing you to join Microsoft clients to a domain and manage them easily. Zentyal Server incorporates all the network services required in a small and medium business environment: * Directory & Domain Server with native compatibility with Microsoft Active Directory * Mail Server with ActiveSync and webmail * Gateway with firewall and proxy * Infrastructure Server with DNS/DHCP server, Certification Authority and Virtual Private Networks For more information and download, please access the project's home page.
    Downloads: 21 This Week
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  • 14
    Cal.diy

    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.
    Downloads: 4 This Week
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  • 15
    WeekToDo

    WeekToDo

    WeekToDo is a Free and Open Source Minimalist Weekly Planner

    WeekToDo is a free minimalist weekly planner app focused on privacy. Schedule your tasks and projects with to-do lists and a calendar. Available for Windows, Mac, Linux or online. WeekToDo is a free and Open Source minimalist weekly planner. With WeekToDo you can start improving your productivity by defining and managing your week and your tasks in an easy and intuitive way. WeekToDo mixes the concept of a calendar and tasks list in a single interface. You can set alarms, colors, recurrent tasks, subtasks, and all this in an intuitive and easy way. Also, we care about your privacy so all your data is stored in your device. WeekToDo is a free and Open Source project available for everyone. You can enjoy it like a native app on Windows, macOS, and Linux or directly from your web browser. It is also available in multiple languages.
    Downloads: 4 This Week
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  • 16
    React Infinite Calendar

    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.
    Downloads: 3 This Week
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  • 17
    pyphoon

    pyphoon

    ASCII Art Phase of the Moon (Python version)

    pyphoon is a small command-line program that renders the current Moon phase as detailed ASCII art directly in your terminal. It computes lunar ephemerides for a given date and location, then maps the illuminated portion onto characters to approximate shading with surprising fidelity. The tool supports showing past or future phases, so you can visualize how the Moon will look on specific dates without opening a browser or an app. It’s intentionally minimal: no GUI, no heavy dependencies, just a quick way to check illumination, age, and phase names in text form. Because it runs cross-platform and works over SSH, it’s popular among terminal enthusiasts and sysadmins who live in the command line. The output can be scripted into cron jobs, motd banners, dashboards, or shared in chat to add a bit of astronomical flair to daily workflows.
    Downloads: 3 This Week
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  • 18
    Defalto

    Defalto

    Fast, modular open source CRM for growing businesses

    Defalto CRM, developed by IT-Solutions4You, is a modern and modular open source CRM system built on over 15 years of real business and CRM development experience. Designed for companies of all sizes, it helps teams manage sales, projects, and customer relationships efficiently through a clean, intuitive interface. The platform combines professional know-how with modern design and functionality. Its free core modules cover essential CRM features, while optional add-ons expand capabilities for advanced business needs. Defalto CRM supports both on-premise and cloud deployment, offering full flexibility and data control. For more info about Defalto CRM visit our page at: https://defalto.com/ Source code available at: https://github.com/IT-Solutions4You/defalto
    Downloads: 11 This Week
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  • 19
    iCal4j
    A Java library for reading and writing iCalendar (*.ics) files.
    Downloads: 7 This Week
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  • 20
    Date Picker Calendar OpenOffice Calc

    Date Picker Calendar OpenOffice Calc

    Date Picker Calendar extension for OpenOffice Calc

    Date Picker Calendar (Latest version 2.60) Set a date in selected cell/cells. Creates a calendar push button in the selected cell and places the date in the cell next to the button. All functions are also in the menu: Tools - Add-Ons. It is possible to change certain settings via the 'Settings' button on the help screen. Calendar Help is located in the help menu of OpenOffice. Toolbar buttons: - Date: the date from the calendar will be inserted in the selected cell/cells. - Date <-Button: a calendar button is created in the selected cell, the date is inserted in the cell to the left of the button. - Button-> Date: a calendar button is created in the selected cell, the date is inserted in the cell to the right of the button.
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    Downloads: 33 This Week
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  • 21
    JDavide
    JDavide (per gli amici JD) è un software gratuito per la gestione dello Studio Legale che aiuta l’avvocato nell’espletamento delle operazioni quotidiane. Funzionalità: pratiche, agenda, formulario, atti, parcellazione, rivalutazione, ecc.
    Downloads: 17 This Week
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  • 22
    Lifeograph

    Lifeograph

    Advanced personal note taking application

    Lifeograph is a diary program to take personal notes on life. It has all essential functionality expected in a diary program and strives to have a clean and streamlined user interface.
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    Downloads: 25 This Week
    Last Update:
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  • 23
    Date Picker Calendar LibreOffice Calc

    Date Picker Calendar LibreOffice Calc

    Date Picker Calendar extension for LibreOffice Calc

    Date Picker Calendar (Latest version 2.60) Set a date in selected cell/cells. Creates a calendar push button in the selected cell and places the date in the cell next to the button. All functions are also in the menu: Tools - Add-Ons. It is possible to change certain settings via the 'Settings' button on the help screen. Calendar Help is located in the help menu of LibreOffice. Toolbar buttons: - Date: the date from the calendar will be inserted in the selected cell/cells. - Date <-Button: a calendar button is created in the selected cell, the date is inserted in the cell to the left of the button. - Button-> Date: a calendar button is created in the selected cell, the date is inserted in the cell to the right of the button.
    Downloads: 30 This Week
    Last Update:
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  • 24
    Kimai - Time Tracking Software

    Kimai - Time Tracking Software

    Time-Tracking for companies and teams with up to 250+ users

    Kimai is web based software that tracks work time, and classifies it. It tracks time and prints out a summary of your activities on demand. Yearly, monthly, daily, by customer, by project, by action. FETCH THE LATEST DOWNLOAD FROM GITHUB: https://github.com/kimai/kimai/releases Record expenses and print customizable invoices in different formats. For further information visit: - https://www.kimai.org - https://www.kimai.cloud - https://github.com/kimai/kimai
    Downloads: 5 This Week
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  • 25
    react-big-calendar

    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).
    Downloads: 1 This Week
    Last Update:
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