WildFly is free and open-source software,[3] subject to the requirements of the GNU Lesser General Public License (LGPL), version 2.1.

In 1999, Marc Fleury started a free software project named EJB-OSS (stands for Enterprise Java Bean Open Source Software) implementing the EJB API from J2EE (Java 2 Enterprise Edition).

Sun Microsystems asked the project to stop using the trademarked EJB within its name.

[5] Wildfly supports a number of features: JBoss EAP itself is open source, but Red Hat charges to provide a support subscription for JBoss Enterprise Middleware.

Before November 2010 JBoss was licensed as annual subscription in bundles of 4 and 32 CPU sockets.