---
title: "How does Lemwatch validate canonical URLs? — Lemwatch Help"
description: "Lemwatch checks every crawled page for a rel=canonical tag, verifies it resolves to a 200, and flags self-referencing errors or canonical loops."
canonical: "https://lemwatch.com/help/canonical-url-checks"
source: "https://lemwatch.com"
---

# How does Lemwatch validate canonical URLs?

> Lemwatch checks every crawled page for a rel=canonical tag, verifies it resolves to a 200, and flags self-referencing errors or canonical loops.

## Quick answer

 On each SEO crawl we look for <link rel="canonical"> on every page, follow it, and confirm the target returns 200. We flag missing canonicals, self-referencing typos, canonical loops, and canonicals that 301/404.

## What we detect

- Missing canonical on indexable pages

- Canonical pointing to a 404 or 500

- Canonical chain (A → B → C)

- Canonical to a noindex page

- Cross-origin canonical without hreflang

## Where to find it in Lemwatch

 **Site → SEO → Canonical**.

## FAQ

### What about paginated pages?

 We treat rel=prev/next as valid canonical alternates.

## Related

- Hreflang monitoring

- SEO monitoring overview


## Related

- [Help centre](https://lemwatch.com/help)
- [How does Lemwatch monitor XML sitemaps?](https://lemwatch.com/help/sitemap-monitoring)
- [SEO Health Monitoring](https://lemwatch.com/help/seo-monitoring)
- [How does Lemwatch check hreflang tags?](https://lemwatch.com/help/hreflang-monitoring)
- [How does Lemwatch validate structured data (JSON-LD)?](https://lemwatch.com/help/schema-structured-data-checks)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [Carbon Footprint Tracking](https://lemwatch.com/help/carbon-footprint)
- [Canonical tag check](https://lemwatch.com/help/canonical-tag-check)