Really Simple Licensing (RSL): Machine-Readable AI Licensing Terms

Really Simple Licensing (RSL) is an open standard for stating, in machine-readable form, the licensing terms on which a publisher's content may be used by AI systems. It was launched in September 2025 and is stewarded by the nonprofit RSL Collective, co-founded by Eckart Walther, a co-creator of RSS, and Doug Leeds, formerly chief executive of Ask.com. RSL 1.0 was designated an industry standard in December 2025, developed with publishers and platforms including Yahoo, Ziff Davis and O'Reilly Media. RSL addresses the question the access and preference layers leave open. robots.txt answers "may you fetch this", and AIPREF answers "may you train on this", but neither says "on what terms" or "for what compensation". RSL encodes the terms themselves. The supported models span the realistic range: - **Free** — use permitted at no cost. - **Attribution** — permitted where the source is credited. - **Subscription** — permitted under a negotiated ongoing arrangement. - **Pay-per-crawl** — compensation each time an AI system crawls the content. - **Pay-per-inference** — compensation each time the content is used to generate a response. Pay-per-inference is the conceptually interesting one, because it prices the use rather than the acquisition. A single crawl that feeds millions of generated answers is worth very differently from a single crawl that feeds none, and per-crawl pricing cannot express that difference. The obvious limitation is enforcement. A declared licence is a statement of terms, not a mechanism — it depends on crawler cooperation, on a collective with the standing to negotiate and audit, or ultimately on copyright litigation. That is why RSL launched alongside a collective rights organisation rather than as a specification alone: the standard supplies machine-readable terms, and the collective supplies the leverage. For a site operating as a Knowledge Commons, the free or attribution tiers are the natural expression. See also The GNU General Public License (GPL): How Copyleft Works for the older tradition of machine-adjacent licence declaration, and The Four Layers of Machine-Readable AI Site Policy.