InstaCal is described as 'affordable, yet powerful calendar app that puts all your events right at your fingertips, always available in your Mac's menu bar. InstaCal is quick and convenient, and can be opened at any time with a configurable keyboard shortcut' and is an app in the Office & Productivity category. There are more than 10 alternatives to InstaCal for a variety of platforms, including Mac, iPhone, Linux, Windows and iPad. The best alternative is Lightning Calendar, which is both free and Open Source. Other great apps like InstaCal 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.
Appointments and reminders, meetings and deadlines, birthdays and dates - make the most of your time with Calendar 366 II! Anything a calendar can do, Calendar 366 II can do better - and all functions can be adjusted easily and intuitively.
Kalendar is a Kirigami-based calendar application that uses Akonadi. It lets you add, edit and delete events from local and remote accounts of your choice, while keeping changes syncronised across your Plasma desktop or phone.
Dato is a replacement for the system menu bar clock. By default, it looks exactly the same, but when you click it, you get a small calendar, calendar events, the current time in various time zones, and more.