GroupCal is described as 'redefines the way calendars work. It introduces a whole new way to create and manage shared calendars between groups of people. Each shared calendar holds events for a specific topic, such as - family, friends, and co-workers' and is an app in the Office & Productivity category. There are more than 25 alternatives to GroupCal for a variety of platforms, including Mac, iPhone, Windows, Linux and iPad. The best alternative is Lightning Calendar, which is both free and Open Source. Other great apps like GroupCal are Rainlendar (Freemium), Apple Calendar (Free), Itsycal (Free, Open Source) and Kontact (Free, Open Source).
Organize your schedule and life’s important events in a calendar that’s fully integrated with your Thunderbird or Seamonkey email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
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.
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. Itsycal has Dark Mode, ISO week numbers, a customizable system clock replacement, and more.
Kontact is the integrated Personal Information Manager of KDE. Kontact suite unites mature and proven KDE PIM applications under one roof. Thanks to the powerful KPart technology, existing applications are seamlessly integrated into one.
Fantastical is a flexible calendar with natural language event creation, a beautiful calendar and event list, support for CalDAV (including Google Calendar delegates) automatic alarms, and instant searching.
Take control of your schedule and get reminded wherever and however you want. Instantly access your appointments, tasks, and notes with a simple glance at a transparent calendar that sits right on your Windows desktop.
Password Encrypted Calendar: Calendar Lock PEA - Displays iCalendars that are plaintext only in RAM, but otherwise always encrypted on the device. - Uses autheticated encryption and a memory-hard key derivation function for the password.
Fantastical 2 includes powerful features such as an incredibly intuitive parsing engine, a full calendar window (with day, week, month, and year views), a quick access mini window, iCloud reminders support, time zone support, and much, much more.