FeedValidator is a useful tool to check your RSS and Atom feeds and even podcasts for feed problems. It will actually highlight where the problem first occurs in your feed. Why would you need a validator for your RSS, Atom feed or podcast? Various web tools might have trouble reading your feeds if they have errors in it. FeedValidator codifies your feed to validate it against rules defined in RSS 2.0 specification.
According to the FeedValidator website:
“It validates RSS feeds against the rules defined in the RSS 2.0 specification. It also validates elements of commonly used namespaces:
* Dublin Core
* mod_content (content:encoded only)
For Atom feeds, it validates against RFC 4287, which describes version 1.0 of the Atom feed format.”
And yes, folks, it’s Open Source.