5 Best Free Open Source Calendar Software for Windows

Here is a list of best free open source calendar software for Windows. These are free desktop calendar software which come with open source license. You can freely download and study source code of these calendar software and even manipulate the source code.

These calendar software let you view the calendar in monthly, daily, weekly, or yearly view. You can also add and schedule important events on particular dates in a month. All of these software provide appointment editor tool to add and manage multiple appointments with date and time, reminder settings, priority, etc. You also get a feature to add and manage various contacts in a few of these software. Additionally, you can create a to-do list in these software to keep up with your daily tasks. You can also add essential notes and memos on particular dates.

In one of these software, you can also import iCalendar files to add calendar events. Also, for students, there is a nice software with features including time table and booklet creator. Other than that, you get various useful features in these software which include task categories creator, email alert generator, setup calendar appearance, reminder tone, etc. In general, these are featured open source calendar software which are useful in keeping up with the dates and managing important tasks.

My favorite Free Open Source Calendar Software for Windows:

BORG Calendar is a good desktop calendar software which comes with a lot of handy tools including appointment editor, tasks creator, memos creator, checklists maker, etc.

qOrganizer is another nice open source calendar software which provides two unique features which are helpful for students. Those features are Time Table Maker and Booklet Maker (with subject marks and absences).

You may also like some best free Holiday Calendar Software, Portable Diary Software, and Open Source Journal Software for Windows.

BORG Calendar

BORG Calendar is a free open source calendar software for Windows. It is a great desktop calendar which shows the current month and highlights important dates and occasion. You can move to previous or next month in the calendar easily. Besides that, it also lets you add and manage events on particular days of a month. Other than that, it comes with a variety of features that you can look forward to.

Main Features of this Open Source Calendar Software:

  • You get different views to open and view calendar including Day, Week, Month, and Year views.
  • It provides an appointment editor using which you can add appointments or other events on a date of the month. In the appointment editor, you get options to customize appointments using options like appointment time, category and other properties (to do, holiday, private, etc.), send reminder email, link files, add URL, priority, popup reminders, etc.
  • It also provides an option to encrypt an appointment.
  • It provides separate tabs to create Memos, Tasks, Todo, Checklists, etc.
  • It lets you add and edit different categories to manage various distinguished tasks.
  • You get a search feature in it to find a specific task, memo, appointment, etc.
  • It lets you edit various program specific preferences including appearance, font, email parameters (SMTP server, SMTP port, reminder email time, etc.), popup reminders, color schemes, Todo options, etc.
  • It provides an Address Book to store various contacts and addresses with information like first name, last name, home address, contact number, etc.
  • You can import iCalendar (ICAL) files from PC or by using URL to import calendar tasks to this software. It also lets you export your monthly events and tasks to the same ICAL file.
  • It contains a CALDAV sync feature too.


BORG Calendar is one of the best free open source calendar software. It contains all those features which you look forward in a desktop calendar including appointment, events, and daily tasks management.


qOrganizer is another free open source calendar software for Windows. It lets you view calendar and manage your daily events and schedules. Let’s checkout a sorted list of features which are provided in it.

Main Features:

  • It lets you schedule several events for a particular date with reminder.
  • You can add important notes on any of the dates.
  • A To-do List feature is provided in it to add multiple tasks with deadline, priority, and its progress.
  • It supports multiple storing modes including text files, SQLite database, and MySQL database.
  • You can print the current calendar view, task view, events, or any other page.
  • It lets you set up general settings such as FTP server, language, reminder type, date format, play sound, etc.

Additional Features:

It provides two handy options which are useful for students:

  • You can also create your weekly time table in this calendar software.
  • It lets you create and manage a booklet with subjects’ marks and absences.


It is a great open source calendar software with some unique and useful features. Students might like to checkout this desktop calendar.


KABE-Calendar is yet another open source calendar software for Windows. It’s like a wall hanging calendar which you can place anywhere on your desktop screen.

Main Features:

  • You can add events on a particular date with name, color, popup time, etc.
  • It also lets you add memos on specific dates.
  • You can also setup tasks with begin day, end day, completion day, color, name, and pop up time.
  • Regular events in month, business day, every week, holiday, etc., can also be added in it.
  • You can also manually add memorial days to your calendar.
  • You can quickly move to previous or next year calendar when needed.
  • It lets you view a list of weekly events and a monthly report.
  • You can also load event data from CSV files.
  • Furthermore, it lets you setup a lot of preferences to customize your calendar including display, font, public holiday, automatic data deletion option, etc.


KABE-Calendar is another nice open source calendar software which you can use to manage monthly events and tasks.

CSC Calendar

CSC Calendar is yet another open source calendar software for Windows, Mac, and Linux. It is a Java based software, hence you need to have Java installed on your system. It is a portable calendar software which requires no installation and can be used on the go.

Main Features of this Portable Open Source Calendar Software:

  • It lets you add appointments on a particular date of the month. You can add appointments with title, location, start time, end time, and notes.
  • You can create and manage multiple contacts in it to add them to specific appointments.
  • You can view all added appointments which can be edited or deleted, as needed.


It is a basic but useful calendar software using which you can manage monthly appointments.


BSPlanner is the next free open source calendar software for Windows. It is a nice and clean desktop calendar which shows monthly calendar.

Main Features:

  • You can add events on a particular date at specific time.
  • To add an event, you can add information like start time, end time, description, repeat, reminder, etc.
  • It lets you add multiple categories to distinguish between different types of tasks.
  • You can set different colors for each category.
  • Some general preferences can also be set in it like reminder tone, calendar view (monthly, weekly, 4 days, daily, events), date format, etc.


It is a simple calendar software with all essential calendar features.

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