What does the validator check for RSS 2.0?

It confirms a single element containing the required , and . Each must contain at least a or a . It also warns when items lack a , which aggregators use to de-duplicate entries.

What does it check for Atom 1.0?

Per RFC 4287 it requires the element to contain , and , and each to contain its own , and . It also warns when there is no feed-level unless every entry supplies one.

Is my feed sent anywhere?

No. The feed is parsed locally using the browser's built-in XML parser (DOMParser). Nothing is uploaded, so you can validate private or pre-publication feeds safely.

Why does it say my XML is not well-formed?

The browser's parser found a syntax error such as an unclosed tag, an unescaped ampersand, or a stray angle bracket. The first line of the parser error is shown. Fix the markup so the document parses, then the element-level checks can run.

Does a clean result mean every aggregator will accept the feed?

It means the required elements defined by the specification are present. Individual readers may impose extra requirements (such as enclosure formats for podcasts), and warnings here flag recommended-but-optional elements you may still want to add.

RSS / Atom Feed Validator

The RSS / Atom Feed Validator checks a pasted feed against the requirements of the RSS 2.0 and Atom 1.0 (RFC 4287) specifications. It tells you which required elements are missing and which recommended ones are worth adding — all parsed locally in your browser.

How it works

The tool parses your XML with the browser’s DOMParser. If the document is not well-formed, it surfaces the parser’s first error and stops. Otherwise it inspects the root element:

<rss> — checks for a <channel> containing <title>, <link> and <description>. Every <item> must have a <title> or a <description>, and a missing <guid> raises a warning.
<feed> — checks (per Atom) for <id>, <title> and <updated> on the feed and on each <entry>, and warns when no <author> is present at feed level.

Issues are grouped by element so you can see exactly where a feed deviates from the spec. Errors indicate a genuine violation; warnings indicate a recommendation.

Example

A feed whose second <item> contains only a <link> — no <title> and no <description> — is reported as an error against that item, because RSS 2.0 requires at least one of the two. Adding a title resolves it.

Notes

The required-element rules follow the published specifications, while warnings cover widely-expected-but-optional fields such as <guid> and feed-level <author>. Because parsing is local, you can validate draft feeds before they ever go live.