iCalSync is a free Android application developed by underscore.inc that allows users to synchronize the calendar of the Android file iCalendar format (.ics) by simply entering the URL of the iCalendar that is published. It is a convenient tool for users who need to keep multiple calendars in sync across different devices or platforms.

The application allows users to register more than one calendar, making it a suitable option for those with multiple schedules. iCalSync is compatible with a variety of applications and can be used to register calendars from a specific link. Users can specify the name, color, and update interval of each calendar. The update interval can be set in seconds and the color can be specified in Hex code without the "#" symbol.