Syndication Feed Discovery

Description

Syndication Feed Discovery

Proposal type:

Interop Investigation

Description:

RSS and Atom remain important parts of the open web, but discovering syndication feeds from a webpage is not handled consistently by modern user agents and related web software.

This is notable because feed autodiscovery is not merely a historical convention. It remains explicitly defined by the WHATWG HTML Living Standard.

HTML allows a webpage to advertise a syndication feed using the link element with the alternate relationship and an RSS or Atom MIME type.

The HTML specification states that user agents performing feed autodiscovery should consider these elements. It also defines how multiple advertised feeds should be considered, including which feed should be treated as the default when a user agent has such a concept.

Despite this standardized mechanism, feed discovery has largely become something applications, browser extensions, and other software must independently implement.

This investigation proposes examining the current state of syndication feed discovery across browser engines and determining what Web Platform Test coverage and testing infrastructure would be necessary to make this standardized part of HTML meaningfully interoperable.

Why an Interop Investigation

The underlying HTML behavior is standardized, but existing Web Platform Test coverage does not appear sufficient to make syndication feed discovery an immediately useful scored Interop Focus Area.

That makes it a good candidate for an Interop Investigation.

The investigation could determine which portions of feed autodiscovery are objectively testable, identify current implementation differences, develop or improve Web Platform Tests, and establish whether syndication feed discovery could become a future Interop Focus Area.

The goal is not to require browsers to ship a built-in RSS reader or restore historical browser UI.

The goal is narrower: determine how the standardized feed discovery mechanism already defined by HTML can be consistently implemented, exposed where applicable, and tested.

Potential investigation scope

The investigation could examine recognition of alternate links using the application/rss+xml MIME type.

It could examine recognition of alternate links using the application/atom+xml MIME type.

It could examine resolution of relative and absolute feed URLs.

It could examine behavior when multiple syndication feeds are advertised.

It could examine selection of the first feed as the default where a user agent implements the concept of a default feed.

It could examine the interaction between the rel, type, href, and title attributes.

It could examine handling of dynamically inserted or modified feed links where applicable.

It could document existing implementation differences between Chromium, Firefox, and WebKit.

It could identify existing Web Platform Test coverage and gaps and determine what additional WPT infrastructure or tests would be necessary to measure interoperability.

The investigation should remain focused on HTML syndication feed discovery rather than attempting to standardize RSS readers, feed presentation, synchronization, or subscription user interfaces.

Specification

WHATWG HTML Living Standard, Link type alternate:

https://html.spec.whatwg.org/multipage/links.html#link-type-alternate

The specification explicitly defines application/rss+xml and application/atom+xml links as references to syndication feeds and describes their use for feed autodiscovery.

Web Platform Tests

Existing Web Platform Test coverage for the complete feed autodiscovery behavior appears insufficient.

Determining the exact coverage, identifying missing tests, and establishing how this behavior can be reliably tested across browser engines would be a primary objective of this investigation.

Developer and user impact

Syndication feeds are one of the web’s oldest mechanisms for allowing users to follow publishers without depending on a centralized service.

Improving interoperability here would not require inventing a new web technology. It would make an existing standardized feature more predictable.

For developers, that could reduce custom discovery code and browser-specific behavior.

For publishers, it could make correctly advertised feeds more reliably discoverable.

For users, it could strengthen an open method of subscribing to websites using software and services of their choice.

The web already has a standard way for a website to say, “This is my feed.”

Interop 2027 can help determine how to make sure software can reliably hear it.

Rationale

Rationale

RSS never disappeared from the web. Browsers simply stopped making much of it visible.

Publishers continue to expose RSS and Atom feeds, and feed readers, aggregators, search tools, podcast applications, and other software continue to consume them. Yet software attempting to discover a site’s feed often needs its own discovery logic.

That can include parsing HTML for alternate feed links, resolving relative URLs, deciding among multiple feeds, following redirects, examining MIME types, and sometimes guessing common feed URLs when discovery fails.

The web already has a standardized mechanism for advertising syndication feeds. Software should not have to behave like a detective to find them.

Consistent and testable feed discovery would benefit publishers because properly advertised feeds would be easier for compatible software to identify. It would benefit developers of feed-consuming software by reducing browser- and platform-specific behavior. Most importantly, it would help preserve a decentralized mechanism for following websites without requiring a proprietary platform, account, algorithm, or API.

This is particularly relevant as interest continues in user-controlled, decentralized, and open methods of consuming content on the web.

Investigation Roadmap

The proposed investigation would focus on bringing standardized RSS and Atom feed autodiscovery to a state where browser interoperability can be objectively measured.

1. Review the current HTML specification for syndication feed autodiscovery, including alternate links using the application/rss+xml and application/atom+xml MIME types.
2. Audit existing Web Platform Tests to identify current coverage and gaps related to syndication feed discovery.
3. Test existing behavior in Chromium, Firefox, and WebKit to document implementation differences.
4. Develop tests covering recognition of RSS and Atom alternate links, relative and absolute feed URLs, multiple advertised feeds, and interactions between the rel, type, href, and title attributes.
5. Investigate behavior for dynamically inserted or modified feed links where the HTML specification defines applicable behavior.
6. Identify cases where current browser behavior or the specification is ambiguous enough to prevent interoperable testing.
7. Where clarification is necessary, work through the appropriate standards venue to resolve specification issues rather than defining new behavior within Interop.
8. Add or improve Web Platform Tests based on the findings so that standardized feed discovery behavior can be measured consistently across browser engines.
9. Determine whether the resulting specification clarity and test coverage are sufficient for syndication feed discovery to become a future scored Interop Focus Area.

Existing specification:

WHATWG HTML Living Standard, Link type alternate:
https://html.spec.whatwg.org/multipage/links.html#link-type-alternate

The goal is not to specify a new RSS reader, subscription interface, or browser UI. The investigation is limited to making the existing standardized mechanism for syndication feed discovery testable and interoperable.

Start by reviewing the WHATWG HTML Living Standard link type alternate section and auditing existing Web Platform Tests for feed autodiscovery. Compare Chromium, Firefox, and WebKit behavior for RSS and Atom alternate links, URL resolution, multiple feeds, and dynamic changes. Done means documented interoperability gaps and a concrete set of WPT coverage or infrastructure improvements.