Question 1

What is a canonical tag?

Accepted Answer

The <link rel="canonical" href="..."> tag tells search engines which URL is the master version of a page. It's how you avoid duplicate content issues when the same content is reachable from multiple URLs (e.g. with/without trailing slash, query params, www/non-www).

Question 2

What common mistakes does this tool check for?

Accepted Answer

Relative URLs (must be absolute), http vs https mismatch, www vs non-www inconsistency, trailing slash inconsistency, presence of query parameters that should be stripped, cross-domain canonical (which is valid but worth flagging).

Question 3

What URL normalization does this tool do?

Accepted Answer

Lowercases the hostname, strips default ports (80 for http, 443 for https), removes duplicate slashes in the path (except after the protocol), and optionally strips common tracking query params (utm_*, gclid, fbclid).

Question 4

What extra features does this tool have compared to others?

Accepted Answer

(1) URL normalization (lowercase host, strip default port, remove duplicate slashes). (2) Pagination canonical (prev/next link tags). (3) Hreflang integration hint. (4) Cross-domain canonical warning. (5) Absolute URL check. (6) Trailing slash consistency check. (7) www vs non-www check. (8) History (localStorage, last 20). (9) Shareable URL — encode the form in the fragment. (10) Batch processing — paste multiple URLs.

Question 5

Is my data sent anywhere?

Accepted Answer

No. Canonical tag generation is pure string/URL manipulation in your browser. History is stored in localStorage on this device only.

Canonical Tag Generator

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