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Really Simple Licensing RSL

Permit Really Simple Licensing (RSL) is an XML vocabulary and set of discovery/authorization mechanisms, published as RSL 1.0 (Document RSL-SPEC-1.0) on 2025-12-10 by the RSL Collective together with named editors from Condé Nast, Ziff Davis, Yahoo, Automattic, O'Reilly Media, Fastly, and Schema.org's RV Guha [1]. It answers the permit question at a finer grain than robots.txt or a bare AI-use preference: it lets a publisher declare not just whether AI systems and crawlers may access or process content, but under what license, for what purposes (indexing, search summaries, AI training, grounding), and at what price.

Overview

The spec bundles four pieces: the core RSL XML vocabulary for expressing usage, licensing, payment, and legal rules; the Open License Protocol (OLP), an OAuth 2.0 extension for acquiring and validating an RSL license at request time; the Crawler Authorization Protocol (CAP), an HTTP authorization scheme for crawlers holding a license; and the Encrypted Media Standard (EMS), a format for encrypting paywalled assets so unlicensed reuse is technically, not just contractually, blocked [1]. Discovery works through robots.txt references, HTML <link> elements, RSS entries, or HTTP files, pointing to an RSL XML license document; an example in the spec shows a publisher prohibiting all AI use (<prohibits type="usage">ai-all</prohibits>) while still allowing search indexing [1].

It does not itself provide agent identity or content delivery; those integrate via OLP/CAP with whatever identity and hosting stack a publisher already runs. It is explicitly an industry specification governed by a vendor consortium (the RSL Collective), not a submission to IETF or W3C — its own document header labels it Category 'Industry Specification', Status 'Recommendation' in RSL's own maturity scale, which should not be read as a W3C/IETF Recommendation.

As of this verification (2026-09-06), RSL 1.0 is current, superseding a 0.9 version referenced from the spec page, with an active GitHub issue tracker and a published errata page — signs of a maintained, living specification rather than a one-off announcement [1]. Given the roster of major media-industry editors (Condé Nast, Ziff Davis, Yahoo, O'Reilly), implementation is recorded as shipping on the publisher side, though this pass did not run a probe to count adoption, so the adoption level is unmeasured rather than claimed or measured.

What is unresolved: how many publishers have actually deployed an rsl.xml file versus simply being named as spec editors; whether any AI vendor has implemented the OLP client side to actually acquire and pay for a licensed RSL grant; and how RSL's paid-licensing model will coexist with the free, binary-only permission signals of AIPREF and Cloudflare's Content Signals Policy, which address the same robots.txt real estate with a simpler yes/no vocabulary.

Discovery and probe

robots.txt reference, HTML <link>, RSS/HTTP header, or a standalone rsl.xml file · /rsl.xml

GET {origin}/robots.txt
parse:     Look for an RSL reference line in robots.txt (pointing to an rsl.xml license file), or an HTML <link> element with an RSL relation, or a Content-License/Link HTTP header; then GET the referenced XML document and parse the <rsl> root element for <license>, <prohibits>, <permits> or <payment> children
on absent: No RSL license file is referenced from any of robots.txt, HTML, RSS, or HTTP headers; the site has not published RSL terms

Live check run by the MCP probe: GET /robots.txt. RSL is referenced from robots.txt by a License line or an rsl.xml link.

{
 "path": "/robots.txt",
 "expect": {
  "text_match": "(?im)^license:\\s*\\S|rsl\\.xml"
 },
 "note": "RSL is referenced from robots.txt by a License line or an rsl.xml link."
}

History

Instances

Every instance with its source is listed on the instances page.

See also

References

  1. The RSL 1.0 specification, Document RSL-SPEC-1.0, Category 'Industry Specification', Status 'Recommendation', was published 2025-12-10 at the canonical URI/namespace https://rslstandard.org/rsl, with editors from RSL Collective, Condé Nast, Ziff Davis, Schema.org, Yahoo, Automattic, O'Reilly Media, and Fastly, and an issue tracker at github.com/rslstandard/rsl. — https://rslstandard.org/rsl (2025-12-10) VERIFIED
  2. The rslstandard/rsl GitHub repository's README independently describes RSL as an open XML-based standard maintained by the RSL Technical Steering Committee, corroborating the spec page's own claims about scope and governance from a second, separately-hosted source, and states the specification's status as 'draft' at the repository level. — https://github.com/rslstandard/rsl VERIFIED

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