free javascript compilers
Browser-based Javascript compiler
FESI (pronounced like fuzzy) is a full implementation of the first version of the EcmaScript language. EcmaScript is largely equivalent to the JavaScript language version 1.1 or to the core part of JScript, but without the navigator specific extensions.
NJS is an independent implementation of the JavaScript language. It used to be called the NGS JavaScript Interpreter, but New Generation Software, the Finnish company who created it, is no longer developing the interpreter. However, due to their choice of license (the GNU LGPL), development has continued. Also, the name NJS was chosen as the old name clashed with both the Linux joystick calibration utility (called obviously enough, js) and the Mozilla shared library of their JavaScript engine.
Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users.
This Mozilla compiler translates JavaScript source into Java class files. The resulting Java class files can then be loaded and executed at another time, providing a convenient method for transfering JavaScript, and for avoiding translation cost.