Manage your daily schedule directly within Thunderbird or SeaMonkey. Lightning Project is a redesign of the Calendar component. Lightning brings the Sunbird calendar to the popular email client, Mozilla Thunderbird and the SeaMonkey internet software suite. Since it's an extension, Lightning is tightly integrated with Thunderbird or SeaMonkey, allowing it to easily perform email-related calendaring tasks.

Lightning is an embedding of the Mozilla calendar code specifically designed to run inside Mozilla Thunderbird.

Features:
1. Help you keep track of your personal schedule
2. Subscribe to calendars on the Internet (via HTTP/WebDAV)

Lightning provides a calendar, to do list, and agenda. Multiple calendars can be setup, so one can have separate calendars for work, home, school, hobbies, events, family, etc. To help setup your calendar, holiday calendars denoting recognized holidays can be imported into Lightning. The holiday calendars are available for download from Mozilla's website.

Requirements:
* Mozilla Thunderbird
* SeaMonkey

The license of this software is Freeware, you can free download and free use this calendar software.