Yes, both Calendly and GitHub offer a Free Trial.
Calendly is designed for Individuals, Freelancers, Large Enterprises, Medium Business and Small Business.
GitHub is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Pricing for Calendly Starts at $8/User/Month when Billed Yearly whereas for GitHub Starts at $4/User/Month.
Some top alternatives to Calendly includes Appointy, Acuity Scheduling, Setmore, Microsoft Bookings, Cogsworth, Book Like A Boss, Doodle, Tidycal, Cal.com, DaySchedule, Google Calendar, Calendar and Zoho Booking.
Some top alternatives to GitHub includes LiveCode, Codeanywhere, Visual Studio IDE, CodeinCloud, GitLive, Microsoft Azure, GitLab, CodeSee and Bitbucket.