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XML format

Atom 1.0

The IETF-standardised syndication format: namespaced from the root, strictly typed, and unambiguous about dates in a way RSS 2.0 never was.

Atom was designed to fix RSS 2.0's ambiguities. It is namespaced from the root, requires ISO 8601 dates, and makes content typing explicit through a type attribute rather than by convention.

It is stricter in ways that matter for tooling: a feed must carry an <id>, a <title> and an <updated>, and each entry must too. That makes Atom considerably easier to consume programmatically, which is why many APIs still emit it.

Constraints that bite

  • Feed and every entry require id, title and updated.
  • Dates are RFC 3339 (ISO 8601), not RFC 822 — the opposite of RSS.
  • <id> must be a permanent, globally unique IRI, not the current page URL.
  • A feed should include <link rel="self"> pointing at its own canonical location.
  • Content type is declared explicitly: type="text", "html" or "xhtml".
Root element
<feed>
Media type
application/atom+xml
Extensions
.xml, .atom
Namespaces
  • http://www.w3.org/2005/Atom
XMLDir label
atom

Specification: RFC 4287

A minimal valid document

Every example on this site is checked against the same parser the workspace uses, so what you see below is known to be well-formed.

atom.xml
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
  <id>urn:uuid:8f1b0c9e-1d3a-4a1f-9d2b-6f0a3c5e7b11</id>
  <title>Example feed</title>
  <updated>2026-07-20T09:00:00Z</updated>
  <link rel="self" href="https://example.com/atom.xml"/>
  <entry>
    <id>https://example.com/first</id>
    <title>First post</title>
    <updated>2026-07-20T09:00:00Z</updated>
  </entry>
</feed>
Validate your own Atom 1.0Extract its XPath map

What goes wrong

12 errors in the corpus declare this format — 10 that stop it parsing and 2 that only appear once a schema is applied. The 10 documented elements of this format are listed there too.

The errors that bite Atom 1.0 documents

Namespaces you will meet

Other formats

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