Let’s Encrypt is a new FREE
certificate authority, built on a foundation of cooperation and openness, that lets everyone be up and running with basic server certificates for their domains through a simple one-click process," its official website explains. "For many server operators, getting even a basic server certificate is just too much of a hassle. The application process can be confusing. It usually costs money. It’s tricky to install correctly. It’s a pain to update.
Check this out https://www.letsencrypt.org/
for open source contributors