1. YouCanBook.me is a cloud-based service which allows your customers to schedule appointments and make bookings.

  2. A wifi connected wall display for your photos, calendar, news, weather and to-do.

    freemium $4.0 / Monthly (Billed annually )

  3. Orage is a new modern calendar application for the Xfce Desktop Environment.

  4. GPS-monitoring : easily record a GPS-track travel and be able to watch an entire group of people.

  5. The Calendar app is a user interface for Nextcloud's CalDAV server.

  6. Material design open source calendar for Android.

  7. KOrganizer is the calendar and scheduling component of Kontact, the integrated personal information...

  8. GNOME Calendar is a simple and beautiful calendar application designed to perfectly fit the GNOME...

  9. Calendar Lock PEA is an encrypted desktop calendar with a day, week and month view. The shown calendars are never stored unencrypted on your disk, but exist only in the RAM. Platform-independent, Open Source, no installation or registration required.

    open-source

  10. OneCalendar is a powerful tool that integrates all your calendars into one easy to read overview. View and manage all your appointments, events and birthdays. Easily filter the information you would like to see. OneCalendar works on Windows 8

  11. California is a new calendar application for GNOME 3. It's currently under heavy development.

  12. TAPIRapps. aCalendar and aCalendar+ for Android. The fastest Android calendar.