NekoHTML inherits from Xerces2.XX. You need to install Xerces2 Java 2.10.0 -zip which is the binary version. You need to make sure you have resolver.jar, serializer.jar, xercesImpl.jsr, xml-apis.jar, nekohtml.jar or else you will get a variety of class not found error mesages andy ou will not be able to do a google search to find out what the cause of hte errors are. This is because there is such a wide variety of use cases which generate error messages with the wrong libraries installed. I installed a version which was on the top of the page but turned out to be Xerces 2.7.X version, then I installed a Xerces-J version but neither had the .jar files mentioned above. This list is hidden under the FaqS. You need Xerces to work before you can use NEKOHtml. There is very little if any documentation on how to use NEKOHtml, you have to read the source code and figure it out. Crappiest UI and one of the most disorganized download pages I have seen.