I want to create a portfolio.
Under references I want to add all my demosites.
Is it possible to add links on these so when somebody is seeing my portfolio and go to my work/or reference section and he clicks on one of those demosites, then he goes to this site and the site opens.
Is this possible within github or do I need to buy a domain name for each site?
Just use github pages. Make a references.html with buttons that are links to your places on github.