Lightning Calendar is a free calendar developed by Mozilla that can be fully integrated with Thunderbird. It allows the user to manage multiple calendars, create a daily to-do list, invite friends to events, and subscribe to public calendar.
Supported Language(s): EnglishDownload Size (Mb): N/A
System Requirements: Thunderbird 38.0.1 or SeaMonkey 2.35
Price: Free
Website: https://www.mozilla.org/en-US/projects/calendar/
Developer: Mozilla
Download: https://www.mozilla.org/en-US/projects/calendar/