Spark is an Open Source, cross-platform IM client optimized for businesses and organizations. It features built-in support for group chat, telephony integration, and powerful security. It also offers a outstanding end-user experience with features like in-line spell checking, group chat room bookmarks, and tabbed conversations.

Combined with the Openfire server, Spark is the easiest and best alternative to using un-secure public IM networks.

Sparkplugs dynamically extend the features of the Spark instant messaging client. Use Sparkplugs to customize Spark for your business or organization or to add an innovative twist to instant messaging. The extensive plugin API allows for complete client flexibility but is still simple and (we hope!) fun to use.
The Spark API provides a framework for adding extensions on top of the protocol and/or UI of the Spark client. For example, you could write your own message filter or add a button to a chat room and send files using the File Transfer API.

Requirements:
* Java.

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