Amaya HTML editor is a tool used to create and update documents directly on the Web. Browsing features are seamlessly integrated with the editing and remote access features in a uniform environment. Amaya started as an HTML + CSS style sheets editor. Since that time it was extended to support XML and an increasing number of XML applications such as the XHTML family, MathML, and SVG. If you also want to manage your MySQL or PostgreSQL database, you can also install a database GUI - NAVICAT. The current releases, Amaya 9.52, is available for Linux, Windows and Mac OS X.
You can display and partially edit XML documents. It's an internationalized application. It's free.