Yes, both GitHub and Currents offer a Free Trial.
GitHub is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Currents is designed for Large Enterprises, Small Business and Medium Business.
Pricing for GitHub Starts at $4/User/Month whereas for Currents Starts at $18.00per 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 Currents includes and undefined.