osTicket - osTicket is a widely-used open source support ticket system.
Jira Service Desk - IT service desk and customer service software by Jira Service Desk. Powerful ticketing system used by 25,000+ organizations. Try it free today.
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
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
OpenRMA - Computer Repair Shop Software. Mobile Repair shop Software and any king of repair shop. Track computer, mobile, tv, jewelry, bike repairs and any king of repair shop.
SolarWinds Service Desk - An IT service management (ITSM) solution that understands what it takes to successfully manage your employee services. Try Solarwinds Service Desk for free!