URL: /rules/ax/rsl-license

---
title: "RSL License"
description: "Checks for a robots.txt License directive pointing to a valid RSL document"
---

Checks for a `License:` directive in `robots.txt` pointing to a valid [Really Simple Licensing (RSL)](https://rslstandard.org) document, plus a matching `rel="license"` link on pages. RSL is a machine-readable licensing standard (v1.0, December 2025) that lets a site state usage terms — including AI-training terms and pay-per-crawl pricing — in a format crawlers can parse instead of a prose page a bot can't act on.

| | |
|---|---|
| **Rule ID** | `ax/rsl-license` |
| **Category** | [Agent Experience](/rules/ax) |
| **Scope** | Site-wide |
| **Severity** | warning (only when the declared license reference is broken; otherwise informational) |
| **Weight** | 1/10 |

<Note>This rule is a **recommendation**: it never penalizes your score. RSL is a young standard; most sites won't have adopted it yet, and that's expected.</Note>

## What it checks

The audit looks for a `License:` line in `robots.txt`:

```txt robots.txt
License: https://example.com/license.xml
```

When present, it fetches the referenced document and validates it as well-formed RSL XML per the v1.0 schema (permissions, prohibitions, and optional payment terms). It also checks representative pages for a matching `<link rel="license" href="...">` tag, which gives page-level tooling (not just crawler-level `robots.txt` readers) a path to the same terms.

Reported outcomes:

- No `License:` directive: informational, no license declared.
- `License:` present but the target doesn't parse as valid RSL: a warning — a declared reference that is broken or malformed misleads the crawlers that honor it.
- Valid RSL document found: informational summary of the declared terms.

## Solution

Publish an RSL document describing your terms and reference it from `robots.txt`:

```txt robots.txt
User-agent: *
License: https://example.com/license.xml
```

```xml license.xml
<rsl xmlns="https://rslstandard.org/rsl">
  <content url="https://example.com/*">
    <license>
      <permits type="train-ai">false</permits>
      <permits type="ai-input">true</permits>
    </license>
  </content>
</rsl>
```

Add the matching `rel="license"` link to your page templates so both crawler-level and page-level tooling resolve to the same document.

## Enable / Disable

### Disable this rule

```toml squirrel.toml
[rules]
disable = ["ax/rsl-license"]
```

### Disable all Agent Experience rules

```toml squirrel.toml
[rules]
disable = ["ax/*"]
```

### Enable only this rule

```toml squirrel.toml
[rules]
enable = ["ax/rsl-license"]
disable = ["*"]
```