Eyes Of Network - EyesOfNetwork (EON) is an open source supervision solution combining a pragmatic usage of ITIL...
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
openITCOCKPIT - openITCOCKPIT is a leading open source monitoring framework based on Naemon (Nagios). In addition it integrates Checkmk and Prometheus. It also offers interfaces to Icinga2, PRTG and opManager to obtain status and performance from them.
HelpScout - Help Scout is a simple, straightforward way to provide excellent support
OTRS ITSM - OTRS ITSM is a fundamental solution for IT Service Management organizations.