Nextcloud Calendar
The Calendar app is a user interface for Nextcloud’s CalDAV server.
20 Alternatives To Nextcloud Calendar
Calendar Lock PEA
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.
Calendarific
Calendarific is a global holiday JSON API and event management & intelligence platform.
ChronoFlo Calendar
ChronoFlo Calendar allows you to make beautiful interactive calendars that you can share on the web.
Desktop-Reminder
Desktop-Reminder is a freeware task planner for Windows to manage your tasks and other to-dos’ in really easy way.
Etar
Material design open source calendar for Android.
Kolab Community
Kolab Groupware is a secure, scalable, reliable, flexible, full-featured collaboration suite.
Lightning Calendar
Organize your life — it’s about time!
One Calendar
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.
Outlook
Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Rainlendar
Rainlendar - Customizable desktop calendar
Simple Calendar
A simple calendar with events (optional recurring and reminders), week numbers and a customizable…
VueMinder Calendar
Take control of your schedule and get reminded wherever and however you want.
XNote Stopwatch
Try the most feature-rich stopwatch and timer software on the net for free!
Zimbra Collaboration Suite
Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more.