JTOpen is the open source version of the IBM Toolbox for Java licensed program product. The IBM Toolbox for Java is a library of Java classes supporting the client/server and internet programming models to a system running OS/400 or i5/OS. The classes can be used by Java applets, servlets, and applications to easily access OS/400 and i5/OS data and resources. The Toolbox does not require additional client support over and above what is provided by the Java Virtual Machine and TCP/IP.