# RSL (Really Simple Licensing)

A License line in robots.txt pointing at an XML licence that says on what terms AI systems may use the content.

**[Access](/docs/access)** · checked once per host (item type `rsl`) · 7 checks that can fail it

It turns a yes-or-no crawl rule into terms: what AI systems may do with the content, and on what conditions, in a file crawlers already read. A crawler that cannot get a valid licence must treat the content as unlicensed, so a broken one gives away nothing it meant to grant and protects nothing it meant to reserve.

## Adoption

**Early production** (L2)

Several independent organisations run it in production, though it is still niche on the open web. Direction of travel: ▲ rising, as of 2026-10-14.

RSL 1.0 became a Recommendation on 2025-12-10, edited by the RSL Collective with Condé Nast, Ziff Davis and Schema.org. Stack Overflow and Medium publish License lines, and Google's Lighthouse stopped calling the directive unknown on 2026-10-09.

| Adopter | Depth | Evidence |
|---|---|---|
| Stack Overflow | production | [stackoverflow.com](https://stackoverflow.com/robots.txt) |
| Medium | production | [medium.com](https://medium.com/robots.txt) |

## What we check

Absence is never a finding: every check below runs only when this technology is detected, so a site that has not
adopted this is not assessed on it and appears in no report.

| Check | Kind | Raises | On whose authority |
|---|---|---|---|
| RSL License Not Absolute | high severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL License Unreachable | high severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL Malformed XML | high severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL Wrong Namespace | high severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL Missing Content | medium severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL Content Missing URL | medium severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL Content Missing License | medium severity | conformance, usability | specification: [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) |
| RSL Partially Assessed | coverage note | nothing | our own coverage |

## Examples

Both run through the same checks as a live scan: the first passes, the second is flagged.

**Correct**

```xml
<?xml version="1.0" encoding="UTF-8"?>
<rsl xmlns="https://rslstandard.org/rsl">
  <content url="/">
    <license>
      <permits type="usage">search</permits>
      <prohibits type="usage">ai-train</prohibits>
    </license>
    <terms>https://example.com/terms</terms>
  </content>
</rsl>
```

**Present but wrong**

```xml
<?xml version="1.0" encoding="UTF-8"?>
<rsl xmlns="https://rslstandard.org/rsl">
  <content>
    <license>
      <permits type="usage">search</permits>
    </license>
  </content>
  <content url="/blog/">
    <terms>https://example.com/terms</terms>
  </content>
</rsl>
```

## Specifications

| Document | Revision | Kind |
|---|---|---|
| [Really Simple Licensing (RSL) 1.0 Specification](https://rslstandard.org/rsl) | RSL-SPEC-1.0, Recommendation, 2025-12-10 | specification |

Last re-read against the published documents: 2026-10-14.