Canonical tag checker. Where does yours point?
How to check a canonical tag
- Paste the full address of the page you want to check.
- Press Check. The tool reads the page's HTML and its HTTP headers.
- Read the canonical URL at the top of the answer, then the problems listed under it.
- If the canonical points at another page on your site, see whether that page answers, redirects or is noindexed.
What is a canonical tag?
A canonical tag is a line in a page's <head> that names the preferred URL for that page's content. Sites use it when the same content can be reached at more than one address, for example with and without tracking parameters.
A page can also send its canonical in an HTTP Link header, part of the server's response. The checker reads both.
<link rel="canonical" href="https://www.example.com/page">What the canonical tag checker reports
The checker reports whether the canonical is missing, cannot be read as an address, appears more than once, or appears outside the <head>. It also flags a relative URL and a URL with a #fragment.
It says whether the canonical points at the page itself or at a different page. It also says whether the page you checked is noindexed, meaning it asks search engines to leave it out of their results.
When the canonical points at another page
If the target is on the same site, the checker fetches it and tells you whether it answers, redirects (and where to), or is noindexed.
The checker names a canonical on another site but does not fetch it.
Common canonical tag mistakes
No canonical tag
The page names no preferred URL at all.
Two canonicals
The HTML and the HTTP Link header both declare one, or the HTML carries two canonical tags. The checker counts every declaration it finds.
A canonical outside the <head>
A canonical link belongs in the <head>. The checker flags one it finds in the body.
A relative URL or a #fragment
The canonical is written as /page in place of a full URL, or it ends in #section. The checker flags both.
A canonical that points at a redirect or a noindexed page
The preferred URL redirects somewhere else, or tells search engines not to index it. The checker fetches same-site targets and reports either one.
The Mastheads canonical tag checker is a free online tool that reads the canonical URL a page declares, in its HTML and its HTTP Link header. It flags a canonical that is missing, declared twice, placed outside the <head>, written as a relative address or carrying a #fragment. When the canonical points to another page on the same site, it checks that page too. It needs no account or email.
Yes. The Mastheads canonical tag checker is free to use online, with no account, no email and no trial to start. Paste a page's address and the answer appears on the same page.
A canonical tag is an HTML link in a page's <head>, written as <link rel="canonical" href="...">, that names the preferred URL for the page's content. Sites use it when the same content can be reached at more than one address. The free Mastheads canonical tag checker reads it for any page you enter.
The canonical URL is the address a page names as the preferred one for its content. A page can name itself, which is a self-referencing canonical, or a different page. The Mastheads canonical tag checker tells you which one a page does.
Paste the page's address into the free Mastheads canonical tag checker and press Check. It reads the canonical from the page's HTML and its HTTP Link header, shows the canonical URL, and lists any problem it finds. Viewing the page source and searching for rel="canonical" also works, but it misses a canonical sent in the HTTP header.
A canonical tag looks like this: <link rel="canonical" href="https://www.example.com/page">. It belongs inside the page's <head>, and the Mastheads canonical tag checker flags one it finds outside it.
A self-referencing canonical is a canonical tag that points at the page it is on. The free Mastheads canonical tag checker tells you when a page's canonical points at itself and when it points at a different page.
A page can declare more than one: two canonical tags in its HTML, or one in the HTML and one in its HTTP Link header. The Mastheads canonical tag checker counts every declaration it finds and flags the page when there is more than one.
A canonical can be written as a relative address, such as /page, in place of a full URL. The Mastheads canonical tag checker works out the full address it points to and flags the canonical as relative.
A page can send its canonical in an HTTP Link header, part of the server's response, as well as or in place of the HTML tag. The Mastheads canonical tag checker reads both and counts them together.
Yes, when that page is on the same site. The Mastheads canonical tag checker fetches the target and reports whether it answers, redirects or is noindexed. It names a canonical on another site but does not fetch it.
A noindexed page asks search engines to leave it out of their results, with a robots meta tag or an X-Robots-Tag header. The Mastheads canonical tag checker tells you whether the page you checked is noindexed, and whether the same-site page its canonical points to is.
Either the page's canonical points to a different address, or the address you typed redirected to another page on the same site. The Mastheads canonical tag checker follows a same-site redirect, checks the page the site served, and says so in the answer.
No. The Mastheads canonical tag checker keeps no copy of your results and asks for no account or email. Mastheads keeps an hourly count of checks and a daily note of which site the tool read, under an identifier made from your IP address, never the IP address itself.
The Mastheads canonical tag checker reads one page at a time. The free Mastheads Quorl scan reads up to 100 pages of a site and reports broken links, duplicate titles, missing meta descriptions and redirects.
Check your whole site. Free.
An SEO crawler that reads the whole site, not one page: Quorl reports broken links, duplicate titles, missing meta descriptions, redirects and the internal linking problems a page-by-page checker cannot see.