Yes, both GitHub and IntelliJ IDEA offer a Free Trial.
GitHub is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
IntelliJ IDEA is designed for Individuals, Freelancers, Large Enterprises, Medium Business and Small Business.
Pricing for GitHub Starts at $4/User/Month whereas for IntelliJ IDEA Starts at $41/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 IntelliJ IDEA includes Codeanywhere, PaizaCloud, Eclipse Che, Visual Studio IDE, Koding, CodeTogether, Flutter, Codefile and Pseudocode Editor.