Closure Compiler results after optimising JQuery (click to here enlarge)
The compiler is available via the command line, a RESTful API, or as a textbox on the Closure Inspector. Asking the compiler to optimise the popular JQuery library results in a 58 per cent reduction in file size but it comes with compilation warnings; making the compiler only remove whitespace gives a 40 per cent reduction with no compilation warnings — although it is outputting only compiler warnings and not errors, I don't promote blind faith in the output of this compiler without some testing first at this point in time.
It also seems that Google has fallen into the homophone hole again. Closure originated in computer science as a programming concept, with Lisp users already having the Lisp dialect called Clojure and Clozure as the common lisp implementation.