RSS, Atom & OPML, freshly brewed.
The complete, modern guide to web feeds, what RSS, Atom, and OPML are, how they work, and why they are quietly everywhere in 2026, plus fast, private, client-side tools to validate, convert, and read any feed. Everything runs in your browser: paste a feed and nothing is uploaded.
Subscribe to the KB Cafe feed: new tools, courses, and posts delivered to your reader.The tools
What is a web feed?
A feed is a machine-readable version of a site’s latest content, a structured list of items (posts, episodes, releases) that software can read without scraping the HTML. Publish one and any reader, podcast app, or script can follow your site and pull updates automatically. Three formats matter:
- RSS (Really Simple Syndication): the classic format, a
<channel>of<item>entries. What most blogs and every podcast still publish. New to it? Start with what is RSS. - Atom: the IETF-standardized alternative (
<feed>of<entry>), stricter and cleaner. - OPML: not a feed itself but an outline format for moving whole lists of feed subscriptions between readers.
How feeds work
Feeds are pull-based. The publisher writes an XML file at a stable URL; a reader polls that URL on its own schedule and shows you whatever is new since last time. Nothing is pushed to you, which is the opposite of a webhook, and it is exactly what makes feeds so durable: no account, no API key, no platform in the middle, just a file and whoever chooses to read it.
A minimal RSS 2.0 feed is just this:
<rss version="2.0">
<channel>
<title>KB Cafe</title>
<link>https://kbcafe.com/</link>
<description>Tools and an interactive AI knowledge base.</description>
<item>
<title>A new tool shipped</title>
<link>https://kbcafe.com/feed-preview</link>
<pubDate>Tue, 16 Jun 2026 12:00:00 GMT</pubDate>
<description>Read any feed as a clean list.</description>
</item>
</channel>
</rss>Paste a real one into Feed Preview to see it as a reader would, or turn it into JSON for your own app.
RSS vs Atom
Both describe the same thing, a list of dated items, and every modern reader handles both. The differences:
| RSS 2.0 | Atom | |
|---|---|---|
| Root | <rss> → <channel> → <item> | <feed> → <entry> |
| Standardized by | A spec led by Dave Winer (2002) | The IETF, RFC 4287 (2005) |
| Strictness | Looser, more forgiving | Stricter, fully namespaced |
| Dates | pubDate (RFC 822) | updated (ISO 8601) |
| Content type | Implied (usually HTML) | Explicit (type="html" etc.) |
| Best when | Maximum compatibility | Publishing a clean new feed |
Validate either against its spec with the RSS / Atom validator.
OPML: your subscriptions, portable
OPML (Outline Processor Markup Language) is how you move a whole reading list between apps.
Export your subscriptions from one reader as a single .opml file, import it into another, and
every feed comes along, no re-adding them one by one. It is also how “blogrolls” and curated
feed bundles get shared. Convert one to and from JSON with the OPML converter.
Feeds in 2026: not dead, just quiet
The web declared RSS dead when Google Reader closed in 2013. It was wrong. Feeds quietly kept running the open parts of the internet: every podcast is an RSS feed, most newsletters have one, and the fediverse is built on the same publish-and-subscribe idea. And there is a new reason to care, AI: language models are starving for clean, structured, permissioned content, and a 25-year-old format turns out to be a very good way to deliver it. We wrote about that in Feeds for Machines, and on why the open web just got quiet.
Why client-side tools? A feed often contains URLs, tokens in query strings, or content you would rather not hand to a third party. KB Cafe’s feed tools parse everything locally in your browser, so a feed you paste never leaves your machine and the tools keep working offline.
FAQ
Is RSS dead?
No, it just got quiet. Every podcast is an RSS feed, most newsletters and blogs still publish one, and the fediverse runs on the same publish-and-subscribe idea. The web stopped talking about RSS around the time Google Reader closed in 2013, but the format never stopped working.
RSS vs Atom, which should I use?
Both work in every modern reader. Atom (an IETF standard) is stricter and cleaner if you are publishing a new feed; RSS 2.0 is more widespread and what most tools expect. If you are just consuming feeds, you rarely need to care which one a site uses.
What is OPML for?
OPML is a simple outline format for moving a whole list of subscriptions between readers. Export your feeds from one app as OPML, import that file into another, and your subscriptions come with you.
How do I subscribe to a feed?
Copy the feed URL (often linked as an RSS icon, or auto-discovered from the page) and paste it into a feed reader like Feedly, Inoreader, or NewsBlur. The reader checks the URL for you and shows new items as they appear.
How often does a reader check a feed?
On a schedule it chooses, usually every few minutes to an hour. Feeds are pull-based: the reader polls the URL rather than the site pushing to it. That is the opposite of a webhook.
Is a podcast really just an RSS feed?
Yes. A podcast is an RSS feed whose items carry an <enclosure> pointing at an audio file. Your podcast app is a feed reader that knows how to play the attachments.
Can I turn a feed into JSON for my app?
Yes, paste the feed into the RSS to JSON tool and you get clean, structured JSON, channel info plus every item, with no server round-trip.
Why will not my feed validate?
Usually unescaped characters (a raw & instead of &), a missing required element, or a mismatched tag. Paste it into the RSS / Atom validator to see exactly what and where.
Does KB Cafe have its own feed?
Yes, subscribe at /feed.xml. Fitting, given the domain’s history: new tools, courses, and posts arrive in your reader automatically.
Related
What is RSS · RSS / Atom validator · OPML converter · RSS → JSON · Feed preview · our RSS feed · What’s new · webhooks vs polling.
In its first life, kbcafe.com was one of the RSS era’s landmark developer resources,
home of The RSS Blog, the Rmail RSS-to-email service, and a shelf of
feed utilities, linked across the early open web. This Feeds section is its modern restoration: the same
subject, rebuilt with private, no-tracking tooling for 2026 rather than left to rot.