Browse free open source Calendar software and projects for Mac and Linux 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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  • 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: 797 This Week
    Last Update:
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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: 632 This Week
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  • 3
    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: 31 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: 78 This Week
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    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: 48 This Week
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  • 6
    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: 31 This Week
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  • 7
    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: 6 This Week
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  • 8
    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: 6 This Week
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  • 9
    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: 25 This Week
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  • 10
    Pendulum

    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.
    Downloads: 4 This Week
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  • 11
    Manage events on a Google Calendar

    Manage events on a Google Calendar

    Manage events on a Google Calendar

    This package makes working with a Google Calendar a breeze. Manage events on a Google Calendar. The first thing you’ll need to do is get credentials to use Google's API. I’m assuming that you’ve already created a Google account and are signed in. Head over to Google API console and click "Select a project" in the header. You can give the service account a name. You can name it anything you’d like. In the service account id you’ll see an email address. We’ll use this email address later on in this guide. Select "JSON" as the key type and click "Create" to download the JSON file. You will get a warning that the service account does not have a role, you can safely ignore this and create the service account without assigning a role. Head over to Google Calendar and view the settings of the calendar you want to work with via PHP. On the "Share with specific people" tab press the "Add people" button and add the service account id that was displayed when creating credentials on the API site.
    Downloads: 2 This Week
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  • 12
    iCalendar Generator

    iCalendar Generator

    Generate calendars in the iCalendar format

    Want to create online calendars so that you can display them on an iPhone's calendar app or in Google Calendar? This can be done by generating calendars in the iCalendar format (RFC 5545), a textual format that can be loaded by different applications. The format of such calendars is defined in RFC 5545, which is not a pleasant reading experience. This package implements RFC 5545 and some extensions from RFC 7986 to provide you an easy-to-use API for creating calendars. It's not our intention to implement these RFC's entirely but to provide a straightforward API that's easy to use.
    Downloads: 2 This Week
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  • 13
    BORG is a calendar and task tracking system written in Java. The calendar provides a nice month view, month-print, email reminders, popup reminders and to do list. The task tracker tracks issues through various states.
    Downloads: 41 This Week
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  • 14
    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: 38 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: 1 This Week
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  • 16
    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: 1 This Week
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  • 17
    openCRX - Enterprise Class CRM

    openCRX - Enterprise Class CRM

    professional CRM and groupware service, ready for the cloud

    openCRX moved to https://github.com/opencrx
    Downloads: 5 This Week
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  • 18
    iCal4j
    A Java library for reading and writing iCalendar (*.ics) files.
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    Downloads: 4 This Week
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  • 19
    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. Source code available at: https://github.com/IT-Solutions4You/defalto
    Downloads: 12 This Week
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  • 20
    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: 4 This Week
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  • 21
    Calendar
    Calendar、Task This is only a read-only mirror repository. Main repository: https://github.com/KangLin/Calendar
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    Downloads: 20 This Week
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  • 22
    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: 11 This Week
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  • 23
    todoyu
    Features: web2.0 project- & task-management, timetracking, team organizing, resource management, calendar, interface for your clients and lots more! Content: see license.txt (file section).
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    Downloads: 3 This Week
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  • 24
    Calizo is a calendar with a zoomable timeline. Unlimited zooming allows to manage historic, genealogical, biographic data, everyday tasks, projects or life plans - for scheduling, genealogy, project management, todo lists, link- and file- organizatio
    Downloads: 6 This Week
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  • 25
    Java-Kalender

    Java-Kalender

    Platformunabhängiger Kalender zum Eintragen von Ereignissen

    Platformunabhängiger Kalender zum Eintragen von Ereignissen mit Erinnerungsfunktion. Beinhaltet alle deutschen Feiertage. Zwischen den Ansichten Jahresansicht, Monatsansicht, Wochenansicht und Tagesansicht kann umgeschaltet werden. Der Kalender kann im Hintergrund laufen und ist personalisierbar. Automatische Erinnerungsfunktion für nahende Ereignisse / Feiertage. Synchronisation über einen FTP-Server möglich.
    Downloads: 17 This Week
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