A calendar extension to Thunderbird
Pros & Cons:
Lightning is an extension to email client Thunderbird.
Although not a standalone calendar program, Lightning is full of features and integrates well into Thunderbird. When creating events, people can be invited straight from Lightning because of its Thunderbird integration, organise staff meetings or parties straight from Lighting by sending the email invites out via Thunderbird.
When creating events, the user can adjust the privacy to just show the event date and time or have the event fully public or private. Webpage links can be attached to events. Although images can't be attached to events, images url's can be. So if you want to attach an image to an event, upload the image to a photo/image sharing website and right click the the image to copy the image url and attach to the event. Much like ReminderFox, only one reminder can be set per event or task, and reminders are in the form of a pop-up.
The user can have multiple colour coded calendars on display at the same time, for example, one for work related events and one for personal events like birthdays. The calendar can be displayed as a daily agenda, weekly or monthly. The user can import calendars into Lightning in the ICS format and export their Lightning calendar to other calendars in the ICS format.
Update: You do not need to install Lightning add-on separately if you're using Thunderbird 38 or newer, which already bundles Lightning together.
Lightning was reviewed by Gizmos Freeware on