IMSDK (Instant Messenger .NET Software Development Kit) is a powerful .NET Component that incorporates Instant Messaging functionality. IMSDK Consists of two sub systems: IM Client and IM Server.
IM Client is a .NET Component that provides all the functionality for the IM Client Users to Send text Messages and file transfers to other IM Clients, Using This IM Client A developer could make a complete Instant Messaging Software Like MSN Messenger and Yahoo Messenger.
IM Server is asp.net Class library that Responds to the request of IM Clients ,IM Server can be added to any ASP.NET page. Performance and stability of IM Server allows to run it for hundred of thousands of users online.
You can download a copy of IMSDK FREE. Trial period is 15 days.