Instantly check canonical tags on any URL. Detect missing canonicals, duplicates, mismatches, and trailing space issues.
The Canonical URL Checker fetches your page's raw HTML and analyzes the canonical tag in the <head> section. It performs 8 checks:
rel="canonical" tag exist?From auditing 85+ SaaS sites, these are the canonical problems we see most often:
Everything you need to know about canonical URLs and SEO.
A canonical URL is the preferred version of a page that you want search engines to index. When duplicate or similar content exists across multiple URLs, the canonical tag (rel="canonical") tells Google which URL is the "master" version. This prevents duplicate content issues and consolidates PageRank to one URL.
A canonical mismatch occurs when the canonical tag on a page points to a different URL than the page's own URL. For example, if page.com/about has a canonical pointing to www.page.com/about (www vs non-www mismatch), Google may get confused about which URL to rank. This often causes the wrong version to appear in search results.
Add a self-referencing canonical tag in the HTML head: <link rel="canonical" href="https://yourdomain.com/your-page-url" />. For WordPress with Yoast it adds automatically; Webflow has a canonical field per page; Next.js uses the metadata API to set canonicals. Every page should have exactly one canonical, either self-referencing or pointing to the definitive version of duplicate content.
Technically yes, but it causes problems. When a page has multiple conflicting canonical tags, Google ignores all of them and treats the page as having no canonical signal. This is worse than having no canonical at all. Always ensure each page has exactly one canonical tag pointing to a single, consistent URL.
Yes. A trailing space in a canonical URL creates an invalid canonical that browsers may parse incorrectly and Google may not recognize. This is a subtle but real issue — Google may treat the URL as malformed and ignore the canonical signal entirely. Always check for and remove trailing whitespace in canonical tags.
A 301 redirect permanently redirects users and search engines from one URL to another — the original URL no longer works. A canonical tag suggests to search engines which URL to index while still serving content on multiple URLs. Use 301 redirects when you want to consolidate URLs permanently. Use canonical tags when you need the same content accessible at multiple URLs but want to specify the preferred one for indexing.
We check every page on your site — canonical tags, schema, speed, Core Web Vitals, and 40+ more signals.
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