jclasslib is released under the GPL.

OS	Downloads
Windows Vista Windows 2000/XP Windows NT 4.0 Windows 98/ME	Setup Executable ZIP Archive
Mac OS X 10.1, 10.2, 10.3, 10.4, 10.5	SIT Archive
Linux x86 RPMs	RPM
Linux / Unix	TAR.GZ Archive

Older version of jclasslib are available from the Sourceforge project page.