An alternative is TestFlight:
https://testflightapp.com/
They offer a hosted solution, so it's not being hosted on your own server, however they provide a lot of features.
There is also a plugin for Jenkins that allows you to publish your builds to TestFlight:
https://wiki.jenkins-ci.org/display/JENKINS/Testflight+Plugin
Also HockeyApp:
http://hockeyapp.net/
They provide a hosted solution using HockeyKit