GlassFish vs Payara: What are the differences?
GlassFish: The Open Source Java EE Reference Implementation. An Application Server means, It can manage Java EE applications You should use GlassFish for Java EE enterprise applications. The need for a seperate Web server is mostly needed in a production environment; Payara: Recognized Leader in Creating Future-Proof Innovative Infrastructure Software. Payara Server is a drop in replacement for GlassFish Server Open Source Edition with quarterly releases containing enhancements, bug fixes and patches.
GlassFish and Payara can be categorized as "Web Servers" tools.
Payara is an open source tool with 699 GitHub stars and 213 GitHub forks. Here's a link to Payara's open source repository on GitHub.