ejabberd

ejabberd is by far the fastest XMPP server I've ever worked with. It's gloriously powerful and just as they say, fault tolerant. My only qualms with it, and why I didn't give it 5 stars, is that it's configuration is not very friendly to tech heavy admins. In other words, I found that configuring it was similar to configuring many unix daemons and such ... often requires you to know what you are doing. The admin interface doesn't "babysit" the admin much. In fact it typically has you typing in exactly what would be in the config file. The language it's written in I find to be difficult to read and follow, and I take my hat off to Alexey for conquering it! The logs are not very clean to look at either. Hrm. Lots of negative things to say here but let me say that beyond these things it's a glorious implementation and I'm always pleased to see new releases coming out. It's easy to see why this and Openfire are often fighting for that number one XMPP server position. =) The fact that jabber.org chose to go with ejabberd says a lot. Great work you all!

There are much more contributors to ejabberd than what ohloh.net claims: see http://ejabberd.jabber.ru/credits for a more complete list (currently around 50 contributors AFAIR).