Yes, both GitHub and HelpDesk offer a Free Trial.
GitHub is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
HelpDesk is designed for Large Enterprises, Medium Business and Small Business.
Pricing for GitHub Starts at $4/User/Month whereas for HelpDesk Starts at $29/User/Month when Billed Yearly.
Some top alternatives to GitHub includes LiveCode, Codeanywhere, Visual Studio IDE, CodeinCloud, GitLive, Microsoft Azure, GitLab, CodeSee and Bitbucket.
Some top alternatives to HelpDesk includes Zoho Desk, Zendesk Support, ManageEngine ServiceDesk Plus, Freshservice, Freshdesk, SupportBee, Teamwork Desk, SysAid, Jitbit Helpdesk, Snappy, Helpspot, ReadyDesk, HelpdeskEddy, Help Desk Premier, Support.cc by 500apps and BoldDesk.