Bopup IM Client Software Development Kit (SDK) is a toolkit for Windows platform that provides documentation, samples and COM components for building powerful instant messaging functionality into existing applications, creating and developing a chat messenger software based a client/server architecture. Applications built on this SDK interact and communicate with Bopup Communication Server (IM server software) that must be installed as a server-side part of the instant messaging system. Bopup IM Client SDK provides functions for connecting and establishing IM session with the communication server, sending/receiving personal and group instant messages, receiving urgent and high-priority tasks from the server, managing user's contacts, receiving presence status updates within the Contact List. This SDK supports various authentication methods to authorize users on the IM server: Simple, Windows Authentication (SSPI) and using Private login and password credentials entered by a end-user.