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.
To use it, simply enter the address of your feed and click Validate. 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.
Why a validator?
Despite its relatively simple nature, RSS is poorly implemented by many tools. This validator is an attempt to codify the specification (literally, to translate it into code) to make it easier to know when you're producing RSS correctly, and to help you fix it when you're not.