Sefira library is meant to provide a well tested and reasonably optimized implementations of some tree comparison algorithms, so that they can be tried out in practical applications. Finding the largest common subtree of two ordered labeled trees is a problem with increasing applications (e.g. in XML processing and computational biology), on which substantial progress has been made in recent years. However, papers on tree comparison may not be available without subscription to the appropriate journals and even when they are, they generally don't contain executable code, so using the new algorithms is non-trivial. Also, there isn't one "best" algorithm yet. Distance definitions differ, and even for the same edit distance, time complexity can be measured on different tree features.
Oxygen XML Diff is a complete solution for comparing and merging XML files. It offers both directory and file comparison, six different diff algorithms, and multiple levels of comparison. The comparison can also be performed inside ZIP-based archives (ZIP, JAR, ODF, OOXML). Oxygen XML Diff includes two specialized XML-aware comparison algorithms: XML Accurate, tuned for precise comparison, and XML Fast, tuned for speed at the expense of some accuracy.