Psi+ is a development branch of Psi XMPP client with rolling release schedule.
https://psi-plus.com/wiki/en:downloadsPsi+ Project
Psi is a cross-platform powerful XMPP client designed for experienced users. It uses classical development model and its releases are quite rare.
Psi+ is a development branch of Psi XMPP client. Thanks to rolling release development model users recieve new features and fixes of bugs very quickly.
For contacting with developers use Psi+ groupchat: xmpp:psi-dev@conference.jabber.ru?join
More information about the Psi+ specific features may be found in wiki.
About Psi+
In 2009 a Psi fork named Psi+ was started. Project purpose are: implementation of new features, writing of patches and plugins for transferring them to upstream. As of 2017 the most of active Psi+ developers have become official Psi developers, but Psi+ still has a number of unique features. From developers point of view Psi+ is just a development branch of Psi IM client which is hosted at separate git repositories and for which rolling release development model is used.
https://psi-plus.com/
https://sourceforge.net/projects/psiplus/