SEO tools
Canonical Tag Checker: See What a Page Declares
Reads the canonical URL a page declares, then fetches that URL to confirm it resolves, is not redirected, and is not noindexed — the three ways a canonical silently becomes inert.
What this canonical tag checker tests
Paste a full URL rather than a bare domain when you want to check a specific page. Canonical bugs are almost always template-wide, so testing one product or article page usually tells you about every page from the same template.
- Whether the page declares a canonical at all, and whether the value is absolute.
- Whether the canonical target returns 200 rather than redirecting or 404ing.
- Whether the target carries a noindex directive, which would cancel the consolidation.
- Whether the canonical is self-referencing or points at a different URL.
Reading the result
| Finding | What it means |
|---|---|
| Self-referencing | The healthy default for an indexable page |
| Points elsewhere | Intentional for a duplicate; a bug if the page is unique |
| Missing | No preferred URL declared; parameter variants can compete |
| Relative value | Legal but risky — resolution errors are easy to introduce |
| Target redirects | Google discards a canonical that points at a redirect |
| Target noindexed | Consolidating onto a page that asks not to be indexed |
A canonical is a hint, not an instruction
Google weighs your declaration against internal links, sitemap contents, redirects, and how similar the pages actually are. When the other evidence points elsewhere it picks a different URL and reports it as the Google-selected canonical. Re-declaring the same tag will not change that — see canonical tag problems for changing the evidence instead, and canonical tag examples for the syntax.
- Why does the checker see a different canonical than my template?
- Client-side scripts can overwrite or duplicate the tag after load. This tool reads the served HTML, which is what a crawler receives before rendering.
- Should every page be self-canonical?
- Every indexable page, yes. It costs nothing and states the preferred URL form before parameter variants appear.
Other tools
Fetches the robots.txt file for the host you enter, reports whether it exists and whether it blocks every crawler, and reads the page-level robots directives alongside it.
Looks for the sitemap the way a crawler does — the robots.txt declaration first, then the conventional locations — then confirms it parses as XML and counts the URLs inside it.
Parses the structured data on the page you enter, lists the schema.org types it finds, and flags blocks that fail to parse or are missing the properties their type requires.
Follows the URL you enter through every hop, reporting the status code at each step and the final destination — the detail a browser hides once the address bar settles.
Fetches the page you enter, takes a sample of the internal links it points at, and requests each one — reporting the status code that comes back instead of the colour of the link.
Checks every signal that decides whether a page is allowed into the index — the status code, robots.txt access, meta robots, the X-Robots-Tag header, and the canonical.
Queries the live DNS for the domain you enter and reports the records it publishes: the addresses it resolves to, where its mail goes, and whether the TXT records email authentication depends on are present.
Queries the registry over RDAP — the structured successor to classic WHOIS — and reports when the domain was registered, how old it is now, who the registrar is, and when the registration lapses.
Enter a domain to find when it was registered, how old it is today, when it expires, and which registrar holds it. Domain age is context for a diagnosis, not a Google ranking factor.
Opens a TLS connection to the host you enter and reports the certificate it presents — the issuer, the validity window, the days remaining, and the negotiated protocol version.
Requests the URL you enter and reports what the server sends back in its headers — the security headers present, the caching policy, whether the response is compressed, and which HTTP version was negotiated.