Canonical Tag Checker
Validate canonical tags from pasted HTML or generate proper canonical link elements. 100% client-side.
Last reviewed: April 2026New to this tool? Click here for instructions
Paste the full HTML source code of a page below. View source with Ctrl+U (Cmd+U on Mac), then copy and paste here.
How to Use the Canonical Tag Checker
To use the Canonical Tag Checker, follow these steps:
1. **View the Page Source**: Open the page you want to check and press Ctrl+U (Cmd+U on Mac) to view its HTML source code.
2. **Copy and Paste HTML**: Copy the HTML source code and paste it into the input area of the tool.
3. **Review the Analysis**: The tool will parse the HTML entirely in your browser and check for the presence, count, format, protocol, and structure of canonical tags.
4. **Switch to Generator Mode**: If you need to create a properly formatted canonical tag, switch to Generator mode and provide a URL. The tool will generate a normalized canonical tag for you.
When to Use the Tool in Real Workflows
Use the Canonical Tag Checker when you need to ensure that your website's canonical tags are correctly set up for SEO. This is particularly important for managing duplicate content and ensuring that search engines index the correct version of your pages.
How It Works
The tool works by parsing the HTML source code you provide. It checks for the presence, count, format, protocol, and structure of canonical tags. In Generator mode, it takes a URL and generates a properly formatted canonical tag that you can use in your website's HTML.
Tips, Edge Cases, or Limitations
1. **Client-Side Limitation**: This tool runs entirely in your browser and cannot fetch live web pages to analyze. To analyze a page, you must view its source code, copy it, and paste it into the tool.
2. **Multiple Canonical Tags**: Only one canonical tag should exist per page. Multiple tags can create conflicting signals that search engines may ignore.
3. **Relative URLs**: Always use absolute URLs for canonical tags. Relative URLs can be misinterpreted if the page is served from different domains or subdomains.
4. **Self-Referencing Canonical**: Every indexable page should have a canonical tag pointing to itself. This is a defensive measure against parameter-based duplicates.
Frequently Asked Questions
Quick reference
| Parameter | Expected Value | Actual Value | Comparison |
|---|---|---|---|
| Canonical URL | https://example.com/page | https://example.com/page | Match |
| HTTP Status Code | 200 | 200 | Match |
| Multiple Canonical Tags | 1 tag | 2 tags | Mismatch |
| Missing Canonical Tag | Present | Missing | Alert |
| Self-Referential Canonical | Same as current URL | Same as current URL | Match |
| Redirects | 301 | 302 | Mismatch |
Example walk-through
Worked example: step-by-step
Step 1. Navigate to the Canonical Tag Checker webpage and locate the URL input field. Enter a valid URL (e.g., https://example.com/page1) and click "Analyze".
Step 2. Paste the HTML source code of the target page into the provided textarea. Ensure the code includes a link rel="canonical" tag (e.g., <link rel="canonical" href="https://example.com/page1">).
Step 3. Click "Check Canonical Tags" to trigger the validation process. The tool will parse the HTML and identify all instances of the canonical tag, step by step.
Step 4. Review the output results displayed in the interface. The tool will show the canonical URL detected, compare it to the page URL, and highlight any discrepancies (e.g., mismatched domains or missing tags).
Sample input:
<html>
<head>
<link rel="canonical" href="https://example.com/page1">
</head>
<body>
</body>
</html>
Step 5. If errors are found, the tool will suggest fixes (e.g., "Canonical URL must match the current page URL"). Use this feedback to correct the tag and recheck.
Expected output:
✅ Canonical tag found: https://example.com/page1
✅ Matches current page URL: https://example.com/page1