JRuby is an implementation of the Ruby programming language atop the Java Virtual Machine, written largely in Java. It is free software released under a three-way EPL/GPL/LGPL license.
License: Open Source
jRuby is a dynamic, object-oriented language that integrates with Java, making it suitable for web development and applications needing Java libraries. Squirrel, on the other hand, is a lightweight scripting language designed for embedding in applications, particularly in gaming and real-time simulations.