Feed Validator - This is a validator for syndicated feeds. It works with RSS 0.90, 0.91, 0.92, 0.93, 0.94, 1.0, and 2.0. It also validates Atom feeds. If the validator finds any problems in your feed, it will give you messages for each type of problem and highlight where the problem first occurs in your feed. If you're unsure what a message means, click the "help" link next to the message for a fuller explanation.

RSS Validator - Feed validation service, enter the url and it would evaluate validity of feed RSS v9x validator.

W3C Validator - a free service that checks documents like HTML and XHTML for conformance to W3C Recommendations and other standards.

Redland RSS 1.0 Validator - Enter the address of an RSS 1.0 feed into the following form and it will be validated and formatted for display.

RSS 1.0 Validator - This prototype is based around a Schematron schema for validating RSS 1.0 by Leigh Dodds.