GlassFish is an open source application server project led by SunMicrosystems for the JavaEnterpriseEdition platform. The commercial version is called SunGlassFishEnterpriseServer. GlassFish is free software, dual-licensed under two free software licences: the CommonDevelopmentAndDistributionLicense (CDDL) 
and the GeneralPublicLicense (GPL) with the classpath exception.

In version 3, GlassFish adds new features to ease migration from TomCat to GlassFish. The other main new features are around modularity (GlassFish v3 Prelude shipped with an ApacheFelix OsGi runtime), startup time (a few seconds), deploy-on-change (provided by NetBeans and Eclipse plugins), and GlassFish v3 "final" is set to be aligned with the upcoming JavaEnterpriseEditionSix release. 

WebSite: https://glassfish.dev.java.net/