Yes, both Desku and Zendesk Support offer a Free Trial.
Desku is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Zendesk Support is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Desku Starts at $19/User/Month when Billed Yearly whereas for Zendesk Support Starts at $19/user/month when yearly.
Some top alternatives to Desku includes Zoho Desk, Zendesk Support, ManageEngine ServiceDesk Plus, Freshservice, MessageDesk, Freshdesk, LiveAgent, HelpDesk, SysAid, Jitbit Helpdesk, eStreamDesk, UseDesk, HelpdeskEddy, Desk360, BoldDesk and Alerty.
Some top alternatives to Zendesk Support includes Zoho Desk, ManageEngine ServiceDesk Plus, Deskero, Support Hub, HelpDesk, Desky, Help Scout, Salesforce Service Cloud, ReadyDesk, Sitehelpdesk, HESK and BoldDesk.