Canonical URL
Check the canonical URL of any page and find canonical tags.
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Canonical URLs are a vital part of technical SEO. They help search engines understand which version of a page is the “master” version, especially when you have multiple URLs with similar content.
What is a Canonical URL?
A canonical URL is an HTML link tag with the attribute rel="canonical". It is used to tell search engines that a specific URL represents the master copy of a page. Using the canonical tag prevents problems caused by identical or “duplicate” content appearing on multiple URLs.
Duplicate A
Duplicate B
→
Canonical
Multiple URLs pointing to one preferred version.
Why are Canonical URLs important?
Duplicate content is a complicated topic, but when search engines crawl many URLs with identical content, it can cause several SEO problems:
- Crawling budget: Google may spend too much time crawling different versions of the same page instead of discovering new content.
- Ranking: Multiple versions of a page compete with each other for rankings.
- Link equity: When people link to your site, they might link to different URLs. A canonical tag consolidates those links into one URL.
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Start SEO AuditWhat is a Canonical Tag?
The canonical tag is the actual piece of code that you add to the <head> section of your HTML. It looks like this:
<link rel=”canonical” href=”https://example.com/main-page/” />
Common Issues with Canonical Tags
1. Self-referencing Canonicals
It is highly recommended that every page has a canonical tag pointing to itself. This prevents duplicate content issues created by UTM parameters, session IDs, or trailing slashes.
2. Relative vs Absolute URLs
Always use absolute URLs (including https:// and the domain name) rather than relative paths (/page/) in your canonical tags to avoid confusion.
3. Multiple Canonical Tags
If a page has more than one canonical tag, Google will ignore both. Ensure your CMS or SEO plugins are not adding duplicate tags.
Canonical Tag vs 301 Redirect
A common question is whether to use a 301 redirect or a canonical tag. A 301 redirect sends the user to the new page. A canonical tag allows the user to see the page but tells Google to credit the SEO value to another URL.
Redirect: URL A → User → URL B
Canonical: URL A → Search Engine → URL B (User stays on A)
Frequently Asked Questions
Does Google always follow the canonical tag?
No, the canonical tag is a “hint” rather than a directive. Google will take it into account, but if they find signals that another URL should be the canonical, they might choose a different one.
Should I canonicalize paginated pages?
Usually, paginated pages (page 2, page 3) should be self-referencing. Do not canonicalize them to the first page of the series.
What about canonical tags on mobile?
If you have a separate mobile site (m.example.com), the mobile page should point to the desktop version as the canonical.