Payara is described as 'Server is an open source, cloud-native application server derived from GlassFish. It supports reliable and secure deployments of Java EE (Jakarta EE) applications on premise, in the cloud or hybrid environments. Commercially supported' and is an app in the Development category. There are more than 10 alternatives to Payara for Windows, Linux, Mac, Java Mobile and Java. The best alternative is Apache Tomcat, which is both free and Open Source. Other great apps like Payara are Jetty (Free, Open Source), Spring (Free, Open Source), Hazelcast (Free, Open Source) and JBoss (Free, Open Source).
Apache Tomcat is an open source software implementation of the Java Servlet and JavaServer Pages technologies. Apache Tomcat powers numerous large-scale, mission-critical web applications across a diverse range of industries and organizations.
Hazelcast is an in-memory Open Source data grid based on Java. By having multiple nodes form a cluster, data is evenly distributed among the nodes. This allows for horizontal scalability both in terms of available storage space and processing power.
JBoss is Red Hats Java EE 5-compliant (soon Java EE 6-compliant) application server. It is, as with Red Hat itself, dual-licensed either as open source (community edition) or commercially (enterprise edition).
GlassFish v3, built by the GlassFish community, is the first compatible implementation of the Java EE 6 platform specification. Many of the Java EE 6 themes carry over to Sun GlassFish Enterprise Server v3 - flexibility, extensibility, and developer ease of use.