With Google Calendar, its easy to keep track of all your lifes important events in one place. You can add events and send invitations effortlessly, share your schedule with friends and family, and search for events you might enjoy.

Your privacy-aware, open-source calendar with intuitive design and multi-platform syncing.

Evolution is a personal information management application that provides integrated mail, calendaring, address book and task list functionality.

Material design open source calendar for Android.

A simple calendar with optional CalDAV synchronization. You can easily create recurring events and setup reminders, it can also display week numbers.

Windows 10 has Mail and Calendar apps already built in.

Rainlendar is a feature rich calendar application that is easy to use and doesn't take much space on your desktop. The application is platform independent so you can run it on all major operating systems: Windows, Linux and Mac OS X.

Morgen merges your calendars, to-dos, productivity apps, and schedulers, so you manage all your time in one place. With Morgen as your time management hub, you’ll stop wasting time flipping between calendars, apps, and browser tabs, and just get work done.

Keep track of your busy schedule and share it with others using Calendar. Create separate calendars — one for home, another for school, a third for work, and so on. See all your calendars in a single window or choose to see only the calendars you want.

Itsycal is a tiny menu bar calendar. If you want, it will display your events as a companion to the Mac Calendar app.

Personal Information Manager (Mail, Contact, Calendar and more).

Calendar encryption: View calendars and stores them encrypted on your device or in the cloud.