RSL: Machine-Readable Content Licensing for AI

RSL (Really Simple Licensing) attaches five machine-readable AI license models: free, attribution, subscription, pay-per-crawl, pay-per-inference.

What is RSL (Really Simple Licensing)?

RSL (Really Simple Licensing) is an open, machine-readable content-licensing standard: a publisher attaches explicit terms for AI use to content as XML an agent can parse, not prose in a terms-of-service page. It launched on 10 September 2025, backed by Reddit, Yahoo, O'Reilly Media and Medium among others; RSL 1.0 became a Recommendation on 10 December 2025, endorsed by more than 1,500 organizations including Cloudflare, Akamai, Creative Commons and IAB Tech Lab (RSL Collective, 2025). The nonprofit RSL Collective maintains it. RSL declares terms; enforcement sits outside the standard, in the CDN or paywall a publisher pairs it with.

Which five license models does RSL offer?

RSL names five license models, from open to metered (RSL Collective, 2025):

• Free — no fee, no required credit.
• Attribution — use it, but credit and link the source.
• Subscription — flat-fee access.
• Pay-per-crawl — "publishers get compensated every time an AI application crawls their content".
• Pay-per-inference — "publishers get compensated every time an AI application uses their content to generate a response".

In RSL 1.0 XML these are the payment types free, attribution, subscription, crawl and use, alongside purchase, training and contribution (RSL Collective, 2025).

How does pay-per-inference differ from pay-per-crawl in RSL?

Pay-per-crawl prices the fetch; pay-per-inference prices the use in an answer. In RSL 1.0 the crawl payment type is "payment every time the content is crawled" and the use type "payment each time the content contributes to an AI-generated output, including use in inference, grounding, or generation processes" (RSL Collective, 2025). Pay-per-inference therefore aligns payment with the value an AI extracts, not with the act of crawling — the better fit for reference material fetched once and cited many times. Neither model meters itself; a CDN or licensing intermediary counts and collects.

How does a crawler discover an RSL license?

RSL 1.0 defines four discovery paths: a License: line in robots.txt, an HTTP Link header with rel="license", an HTML link element, or an RSS feed (RSL Collective, 2025). The XML then declares per usage type — search, ai-input, ai-index, ai-train, ai-all or all — what is permitted under which payment type. This site practices it: /license.xml permits search and ai-input free, licenses ai-train as a purchase at a demo price of USD 25.00, and the server advertises the file in an RFC 8288 Link header with rel="license" (AGENTS WELCOME, 2026).

RSL content licensing — frequently asked questions

What is pay-per-inference, and how does it differ from pay-per-crawl?

Both are usage-priced RSL license models. Pay-per-crawl (RSL 1.0 payment type crawl) prices the fetch — the publisher is paid every time the content is crawled. Pay-per-inference (payment type use) prices the use in an answer — the publisher is paid each time the content contributes to an AI-generated output, aligning payment with the value an AI actually extracts.

How does a crawler find an RSL license?

Through a License: line in robots.txt, an HTTP Link header with rel="license", a link element in the HTML, or an RSS feed — RSL 1.0 defines all four. This site sends the Link header and publishes the license at /license.xml.

Does RSL enforce its terms?

No. RSL declares terms machine-readably; enforcement sits outside the standard, in the CDN, paywall or licensing intermediary a publisher pairs it with. Cloudflare and Akamai are among the 1,500-plus organizations endorsing RSL 1.0.

Which usage types can an RSL license permit?

RSL 1.0 defines six: all, ai-all, ai-train, ai-input, ai-index and search. A license can permit search and ai-input while pricing ai-train — the pattern this site's own license follows, with search and AI input free and training licensed.

Who maintains RSL, and is it final?

The RSL Collective, a nonprofit led by Doug Leeds and Eckart Walther, co-creator of RSS. RSL 1.0 has been a Recommendation since 10 December 2025.

Related: RSL licenses content to AI across five models · RSL defined in the Lexicon · the pay-per-crawl mechanism explained in full · every mechanism is specified by a Layer-6 licensing protocol · back to AI access economics · audit your site.

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