Calify allows you to open calendar files and event invitations in a variety of web calendars.

Double-click an *.ics file and see it open in, e.g. Google Calendar. Automagically.

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version 1.0.0 for Windows 7/8/8.1/10/11 screenshot
Flexible
Multiple web calendars are supported, including Google Calendar, Outlook.com Calendar and Yahoo! Calendar.
Integrated
Installation creates a system wide file association for iCalendar files (*.ics).
From The Blog
Introducing Calify
As a vivid user of Google Calendar, I have always lacked the ability to open event invitations or calendar files directly in Google Calendar.