A canonical tag checker verifies the <link rel="canonical"> tag in your HTML for correctness — checking it exists, uses an absolute HTTPS URL, doesn't conflict with og:url, and isn't contradicted by a noindex directive. Paste your HTML to get instant analysis.
Paste Your HTML Source
Extracted Canonical URL
Canonical Tag Analysis
Related SEO Tags Found
Paste your HTML and click "Check Canonical Tag" to see the analysis
How to Use the Canonical Tag Checker
The canonical tag checker parses your HTML using DOMParser and runs 8 checks on the <link rel="canonical"> tag — verifying existence, absolute URL format, HTTPS protocol, single usage, self-reference status, og:url alignment, head placement, and noindex conflict. This covers the most common canonical implementation mistakes that hurt SEO.
Step 1: Get Your Page's HTML Source
Open your page in a browser and press Ctrl+U (Windows) or Cmd+Option+U (Mac) to view the HTML source. Copy the entire source code, or just the <head> section if you want faster analysis. Paste it into the input box above. The tool works with raw HTML and does not need to fetch any URLs.
Step 2: Run the Canonical Analysis
Click "Check Canonical Tag" to analyze. The 8 checks cover: canonical tag existence (missing canonical is a common error on paginated pages), single canonical (multiple canonicals send conflicting signals), absolute URL format (relative URLs like "/page/" instead of "https://example.com/page/" are invalid), HTTPS protocol (HTTP canonicals on HTTPS sites confuse Google), self-referencing vs cross-page (flags when the canonical points elsewhere for awareness), og:url match, head section placement, and noindex conflict.
Step 3: Review the Related SEO Tags
The related tags section shows additional signals found in the HTML: og:url value, meta robots content, the page's title, and all <link rel="..."> tags. This helps identify conflicts — for example, if og:url is HTTP while canonical is HTTPS, or if robots contains "noindex" while a canonical exists. Use this overview to make sure all signals point to the same intended URL.
Step 4: Fix Canonical Issues
The most common fixes are: add a self-referencing canonical to every page, ensure the URL is absolute and uses HTTPS, remove duplicate canonical tags (keep only one), and resolve noindex conflicts by deciding whether the page should be indexed. After fixing your HTML, re-paste it to verify the issues are resolved. Every page on your site should have exactly one absolute HTTPS self-referencing canonical tag.
FAQ
Is this canonical tag checker free?
Yes, completely free with no account or signup required. All processing happens in your browser — your HTML is never sent to any server. You can safely analyze private, draft, or staging pages.
What is a canonical tag and why does it matter?
A canonical tag (rel="canonical") tells search engines which URL is the preferred version of a page when multiple URLs show the same or similar content. Without it, Google may split ranking signals across URL variants (with/without www, HTTP vs HTTPS, trailing slash, UTM parameters), diluting your page's ranking power.
What happens if a page is missing a canonical tag?
Without a canonical tag, Google self-selects the canonical — often choosing correctly but sometimes picking a less-preferred URL variant like the HTTP version instead of HTTPS. Missing canonicals are a common issue on paginated pages, filtered product listings, and pages with tracking parameters. Adding an explicit self-referencing canonical eliminates ambiguity.
Should the canonical URL always point to itself?
Not necessarily. A self-referencing canonical (pointing to the current page) is standard for unique pages. Canonicals that point elsewhere are used intentionally — for example, a paginated page canonicalizing back to the main collection page, or a printer-friendly version canonicalizing to the original. This tool flags whether the canonical is self-referencing or cross-page, and you decide which is correct.
What does it mean if canonical and og:url differ?
The canonical URL tells search engines the preferred URL for indexing. The og:url controls the URL used for social media sharing attribution and click tracking. If they differ, it's not always an error — but it can cause inconsistency in analytics. If both should point to the same canonical page URL, make them match.
What is a conflicting noindex + canonical?
If a page has both a canonical tag pointing to itself and a meta robots noindex directive, this is contradictory — you are telling Google both to index this URL (via canonical) and not to index it (via noindex). Google will generally honor noindex over canonical, meaning the page won't be indexed. This is a common mistake on staging sites where noindex is added but the canonical accidentally remains.
Why should the canonical URL use HTTPS?
Google has used HTTPS as a ranking signal since 2014. If your canonical tag points to an HTTP URL but your site is served over HTTPS, Google may redirect to HTTPS anyway, but the explicit HTTP canonical sends a confusing signal. Always use HTTPS canonical URLs on HTTPS sites.