Validator.nu — Validation 2.0

Validator.nu is an (X)HTML5 validator and a general-purpose RELAX NG and Schematron-based online XML validator. The HTML5 facet features a reusable implementation of the HTML5 parsing algorithm and validation of XHTML5 + SVG + MathML compound documents. The general-purpose facet allows customization with user-provided schemas. In addition to a HTML form-based user interface, the service offers its full functionality through a RESTful XML and JSON Web service API.

An overview of the software architecture is given with emphasis on functionality implemented during the past year. The Web service API is presented as a potential way of integrating validation into blogging systems, authoring work flows, Ajax mashups or browser extensions without having to run the software in-process. The Validator.nu HTML parser is presented as an easy way to add HTML5 parsing to Java applications.