The Discovery dimension asks whether machines can find the work. A feed is the cheapest mechanism for that, and there are three formats to choose between. This page sets out what actually differs between them.
The three formats
| Format | Published | Syntax | MIME type |
|---|---|---|---|
| RSS 2.0 | 1999 onward | XML | application/rss+xml |
| Atom 1.0 | 2005, RFC 4287 | XML | application/atom+xml |
| JSON Feed | 2017, v1.1 current | JSON | application/feed+json |
What actually differs
Required fields. RSS 2.0 requires a feed-level title, link and description, but requires nothing of individual items. Atom 1.0 requires that both the feed and every entry carry a title, a unique identifier and a last-updated timestamp. In practice that makes Atom feeds more reliably parseable, because a consumer can depend on an ID and a date being present.
Content ambiguity. RSS 2.0 may contain either plain text or escaped HTML with no way to signal which. Atom specifies content types explicitly. This is the single most cited technical criticism of RSS and the reason Atom exists.
Self reference. Atom feeds carry a self link, so a reader knows the feed canonical location. RSS feeds commonly add this by borrowing the Atom namespace.
Syntax. JSON Feed is functionally equivalent to the other two. Its argument is that JSON is easier to generate and parse than XML for most developers. It is not more capable.
Which one to publish
The JSON Feed authors themselves are direct about this: if you can only publish one format, publish RSS, on the grounds that it is time-tested and widely supported. They also advise that anyone already publishing RSS or Atom should continue to do so.
That is the practical answer. Reader and aggregator support for RSS is effectively universal. Atom support is close behind. JSON Feed support is real but partial, and it is generally shipped alongside RSS rather than instead of it.
Full text or excerpt
This is a publishing decision rather than a format one, and every format supports both. An excerpt feed requires the reader to visit the site to finish reading. A full-text feed does not.
The trade is genuine and it is not settled by evidence we have. Anyone claiming a universal answer is asserting rather than measuring. What is checkable is which one a publisher chose, and whether that choice is consistent with the rest of their distribution strategy.
How this is scored
Discovery asks whether a feed exists, whether it is valid, and whether it is discoverable via a link tag in the document head. Format choice is not scored. Publishing no feed at all is.
Sources
Verified August 2026.