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.
Amatix Office is a complete communication platform for small and medium-sized businesses. It provides email, calendar, contacts, conventional telephony like ISDN, new generation VoIP telephony like SIP, instant messaging, presence, and other features needed to power a business. Amatix Office is very easy to install and use and does not require any special IT skills. It is a live software appliance which boots a computer directly from a CD or USB flash drive without any software installation.
nimsg (the Network Instant MeSsenGer) is a compact, server-based chat program. Its features include the ability to chat with more than one person at the same time, the ability to post multiple times in a row, and the ability to let users choose their in-chat nicknames. It can be used as an alternative for IRC, for those times where you just want to have a small, local chat room.
Messenger++ is a multi-protocol instant messaging client for Android. It features multi-protocol support (currently: XMPP, Facebook(XMPP), Google Talk(XMPP), VK, SMS) + audio calls if supported by the protocol. The UI is optimized for tablets. It is a Maven-based project with Robolectric tests built by Travis CI.
SecuXabber is a secure Jabber-client for Android that uses strong, asymmetric encryption on top of the XMPP protocol. A key pair is generated on application start-up. Users can send their public key to other SecuXabber users via Bluetooth. This face-to-face check ensures the veracity of the public key. After the keys have been imported by both users, all communication between them is encrypted using strong 4096 bit encryption. It supports all relevant XMPP features, works with multiple accounts, is highly customizable, and has many other useful features.