Yes, both GitHub and Slenke offer a Free Trial.
GitHub is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Slenke is designed for Large Enterprises, Medium Business and Small Business.
Pricing for GitHub Starts at $4/User/Month whereas for Slenke Starts at $15/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 Slenke includes Smartsheet, Miro, Process Street, Wrike, Notion, TeamGantt, monday.com, Teamwork, ProjectManager.com, Microsoft Project, ProWorkflow, Projectworks, Trackboard, Quick Base, ClickUp and Project Insight.