Validator

This is a validator for syndicated feeds. It works with RSS 0.90, 0.91, 0.92, 0.93, 0.94, 1.0, 1.1, and 2.0. It also validates Atom feeds. To use it, simply enter the address of your feed and click Validate.

This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc. If you wish to validate specific content such as RSS/Atom feeds or CSS stylesheets, MobileOK content, or to find broken links, there are other validators and tools available.

This page lists some of the tools provided by the W3C in the domain of Quality Assurance: validators and other test tools. Almost all of these tools are web-based, are available both as downloadable source, and as free services on the w3.org site.

EpubCheck is a tool to validate IDPF Epub files. It can detect many types of errors in Epub. OCF container structure, OPF and OPS mark-up, and internal reference consistency are checked. EpubCheck can be run as a standalone command-line tool, installed as a web application or used as a library.