jabberd is a Jabber/XMPP instant messaging server. It implements XMPP-Core (RFC3920), XMPP-IM (RFC3921), and a range of protocol extensions: XEP-0012, XEP-0016, XEP-0030, XEP-0049, XEP-0054, XEP-0077, XEP-0079, XEP-0092, XEP-0114, XEP-0138, XEP-0153, XEP-0157, XEP-0160, XEP-0191, XEP-0192, XEP-0193, XEP-0198, XEP-0199, XEP-0202, XEP-0203.
Gtk-Gnutella is a full-featured Gnutella client using GTK+. It contains all widely deployed Gnutella features, including DHT support. It is extremely efficient, using little CPU time and memory. It is meant to be left running 24x7. It is fully compatible with UPnP and NAT-PMP, and as such is easy to use behind a firewall supporting one of these port mapping technologies.
Grapple is designed to be a simple network layer, allowing the addition of multiuser features to an application for as little as a dozen lines of code. However, it also allows for more. It features simple client-server networking that keeps all clients aware of all other clients, passworded servers, and data transfer via TCP, UDP, or reliable UDP. Advanced features include network messaging via push, pull, or a combination, multiple methods of querying users, user groups for client bandwidth saving, network load reacting data transmission and retransmission, background pinging to monitor network states, server failover, and a fully functional lobby system.