Mozilla's standalone JavaScript interpreter is one of two options for supporting PAC in libproxy. (The other is JavaScriptCore from WebKitGTK.) It is already in all major distros. http://cygwin-ports.git.sourceforge.net/git/gitweb.cgi?p=cygwin-ports/js ftp://ftp.cygwinports.org/pub/cygwinports/uploads/js185/ Yaakov