Being an open-source product, Zammad is free for you to host yourself. It also includes SSO out-of-the-box and other helpful features. Thus, it's got a very low barrier to entry with no complicated authentication matters. It allows multiple agents, tagging, and for ticket categorization. Review collected by and hosted on G2.com.

It's not as polished as products like ZenDesk. In fact, it's not really an awesome experience. Some things you'd think ought to be standard are either not implemented or not implemented well or a bit clunky. For instance, it's laborious to try and find agent performance metrics. Really, it's more a system for tracking your currently open tickets but without a lot of richness in managing performance or reviewing history, finding root causes, identifying trends, etc. Review collected by and hosted on G2.com.