Here is a rewrite engine that has a "lite" free version: http://www.isapirewrite.com/ Another alternative that comes highly recommended from a colleague: http://www.motobit.com/help/url-replacer-rewriter/iis-mod-rewrite.asp I haven't personally used either of these products. I've always done all of my url-rewriting at the application level (using global.asax in .net apps). But they appear to meet your criteria (both are free).