XIFF is an Open Source Flash library for instant messaging and presence clients using the XMPP protocol. XIFF includes an extension architecture that makes it easy to add functionality for additional protocol extensions, or even your own special-needs extensions. There are quite a few extensions already included in the library, giving it support for XML-RPC over XMPP (XEP-0009), Multi-user conferencing (XEP-0045), Service browsing (XEP-0030), and XHTML message support (XEP-0071).