Here. "The primary purpose of the tool is to be able to quickly detect node-level changes between versions of an XML document, and with enough granularity to support efficient patch and merge scenarios. The patch format can be used for fairly terse delta-encoding to transfer incremental changes across the wire as well. The tool is officially called "XmlDiff and Patch" and is implemented in managed code (sorry, no MSXML version). Currently you can only perform XML Diff through the web page, but the assembly should be available on that site very soon. I think it is considerably better than anything else available today, in terms of both performance and accuracy, and the API is a good fit with the System.Xml libraries, so it should be really easy for any VB/J#/C#/F# programmers to use."