The XMLSpy XML Editor includes a visual XML diff tool that allows developers to easily compare and merge XML documents and directories in an intelligent, XML-aware manner. It allows you to compare two XML files as well as to compare three XML files.
The XMLSpy XML diff/merge engine is completely customizable. For example, you can specify if entities should be resolved, if namespace prefixes, whitespace, CDATA, processing instructions, comments, or the ordering of attributes/child elements should be ignored or not, and how to visualize differences.
In addition, you can merge the textual differences and differences in XML between two or three files as you are comparing them.
The nature of XML means text-only compare tools fall short in these important scenarios:
If you don't need a complete XML editor like XMLSpy, or if you need to diff other source code files, you can choose DiffDog for file, directory, and database comparisons.
DiffDog also supports XML-aware comparisons, including graphical XML Schema differencing and will automatically generate an XSLT stylesheet to transform XML documents to the new XSD.
You can download a free trial of DiffDog, or test drive the MissionKit tool suite, which includes both XMLSpy and DiffDog.
Choose the specially-priced Altova MissionKit to get both XMLSpy AND DiffDog compare tools - plus 5 other development software products - for less than the price of two.