This is a fantastic and essential editor for anyone working with XML and its related technologies (XSLT, XQuery, XML Schemas, RelaxNG, DTD). If you work with TEI, DocBook, or DITA, oXygen ships with up-to-date versions of these schemas and templates. oXygen natively understands (and learns) XML structures, so you'll notice it suggesting element and attribute values as you edit. It's also an excellent XHTML, CSS, and plain text editor. Its built-in ability to browse and query native XML databases (such as eXist and Mark Logic), SQL databases, and SVN repositories make it a tool for the power user. While Java-based and thus visually non-Mac in UI, the developers are listening to the requests of mac users in their forums. Like many specialized tools, oXygen's many views and palettes let you customize your UI to expose only what you need to get your job done. Lastly, don't let the price scare you away! There price listed here is for the professional commercial license. The personal/academic price is much lower (currently $48). The fact that this license is cross-platform means that if you have a windows machine you can install it there too and get work done. Since I purchased in November, two point releases have come out - 9.2 and 9.3 - and I've been impressed with the steady progress they've made. 9.3 is able to open MS Office XML files in their zipped state from within oXygen. They're also adding more options for WYSIWYG-like XML editing, which make it nicer to edit XML files (and to train XML newbies to edit XML files). My only problem cropped up when I began editing a fairly large XML file - I started getting out of memory errors. This was solved by a quick edit of a config file (oxygenmac.sh) in the oxygen directory... Java apps apparently can't adjust their memory as needed as native mac apps can. But the steps for doing this were well laid out in the included documentation.