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Canonical Tag Checker

Check a page’s rel="canonical" tag: whether it exists, whether it points at itself, another page, or another domain entirely.

No account needed. https:// is assumed if you leave it off.

What the canonical tag does

A rel="canonical" link tells search engines which URL is the preferred version of a page when several URLs serve similar content. Tracking parameters, session IDs, pagination, print views and http/https or www/non-www variants all create duplicates, and without a canonical the search engine picks a winner on its own.

Google treats the canonical as a strong hint rather than an instruction. It can and does override it when the signals disagree — for example when your internal links, sitemap and canonical all point at different URLs. Consistency across those three is what makes the canonical stick.

The dangerous cases are the ones this checker calls out specifically: a canonical pointing at another domain (which hands your ranking to that site), and more than one canonical tag on a page (which makes Google ignore all of them). Both are usually the result of two systems — a theme and an SEO plugin, say — each adding a tag without knowing about the other.

How to Fix Common Canonical Tag Checker Issues

Reference guide for resolving the most frequent configuration errors and warnings.

The page has no title tag

Without a <title>, Google generates one from the page content — usually the h1 or anchor text pointing at the page. You lose control of the single most visible line in the search result.

The Fix: Add a <title> inside <head>. Put the distinctive part first, since the end is what gets cut off.

<title>Robots.txt Tester - Check if a URL is blocked</title>

The title is wider than Google displays

Google truncates titles by rendered pixel width, not character count. Anything past roughly 580px is replaced with an ellipsis, so the end of your title never reaches the reader.

The Fix: Move the important words to the front and cut the tail. Brand suffixes are the usual thing to shorten or drop — they are the least useful part of the line.

The title is very short

A short title is not an error, but it leaves visible space unused and often means the page is not describing itself fully.

The Fix: Add the qualifier a searcher would actually type — the location, the format, the year, the specific problem being solved.

No meta description

Google will write a snippet itself, pulled from wherever on the page seems to match the query. It is often a reasonable snippet — but it is not the one you chose.

The Fix: Add a meta description in <head> that makes the case for clicking, written for a person rather than for a keyword count.

<meta name="description" content="Free robots.txt tester. Test any URL path against a site’s rules and see exactly which directive blocks it.">

The description will be truncated

Past roughly 920px of rendered width the snippet is cut off. Everything after the cut is invisible in the result.

The Fix: Put the reason to click in the first sentence, and treat anything after that as a bonus that may never be seen.

No canonical tag

Google picks a canonical for every page whether you specify one or not. Without the tag, that choice is made for you — and on sites with query parameters or duplicate paths, it is often the wrong URL.

The Fix: Add a self-referencing canonical to every indexable page. It is the cheapest insurance against duplicate-content ambiguity.

<link rel="canonical" href="https://example.com/blog/post">

More than one canonical tag

When a page declares several canonicals, Google treats the signal as unreliable and ignores all of them. This usually happens when a CMS and a plugin both add one.

The Fix: Leave exactly one. Check for a theme and an SEO plugin both injecting a tag into the head.

The canonical points at a different domain

This page is telling Google that the canonical version lives on another site, so the other site is the one that should rank. That is correct for syndicated content and a serious bug otherwise.

The Fix: If this is your page, point the canonical at itself. Cross-domain canonicals should only be used when you deliberately want the other URL to rank instead.

Frequently Asked Questions

How long should a title tag be?
Aim to stay under about 580 pixels, which is roughly 50-60 characters for typical English text. Put the distinctive words first, because the end is what gets cut.
Will Google use my meta description?
Sometimes. Google rewrites descriptions when it thinks a different snippet matches the query better. Writing one still helps: it is used often enough to matter, and without one you have no say at all.
Should every page have a canonical tag?
Every indexable page should have one pointing at itself. It costs nothing and it removes the ambiguity that duplicate URLs, tracking parameters and pagination otherwise create.
Why does the preview differ from what I see in Google?
Google rewrites titles and descriptions for a meaningful share of results, based on the query. This preview shows what your tags say; Google decides what to display.

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