What is a canonical tag?
A canonical tag is an HTML element — <link rel="canonical" href="…"> — placed in the <head> of a page. It tells search engines which URL is the preferred, authoritative version when the same content is accessible at multiple URLs. Canonical tags prevent duplicate content penalties and consolidate link equity to the correct page.
What does a self-referencing canonical mean?
A self-referencing canonical is when the canonical tag on a page points to that same page's own URL. This is the correct and ideal state — it clearly signals to search engines that this URL is the master version. Every page that is the definitive source for its content should have a self-referencing canonical tag.
What is a missing canonical tag and why is it a problem?
A missing canonical tag means the page has no <link rel="canonical"> element at all. Without it, search engines must guess which URL to treat as canonical — often resulting in duplicate content issues, diluted link equity, and unpredictable indexing. Every public-facing page should explicitly declare a canonical tag.
What is a canonical mismatch?
A canonical mismatch occurs when the canonical tag on a page points to a different URL. This may be intentional — for example, a paginated page canonicalising to the first page — but it frequently happens accidentally during CMS updates or template changes. Mismatched canonicals should always be audited to confirm they are deliberate.
What is a chained canonical?
A chained canonical occurs when Page A canonicalises to Page B, but Page B has a canonical tag pointing to Page C. Search engines may not follow canonical chains reliably. Google recommends ensuring that the final canonical destination self-references — breaking the chain at source.
How many URLs can I check at once?
The TechOreo Bulk Canonical Checker supports up to 200 URLs per batch. If you paste more than 200 URLs, the tool automatically trims to the first 200 and shows a notification. For audits larger than 200 pages, run multiple batches.
Why might a canonical check return an error?
A canonical check returns an error when the page cannot be fetched. Common causes include: the page is behind a login or paywall, the server blocks automated requests (e.g. via robots.txt or rate limiting), the URL returns a non-200 HTTP status code, or the CORS proxy is temporarily unavailable for that domain.
Can I export the canonical audit results?
Yes. You can download the full results as a CSV or JSON file. There is also a dedicated Issues CSV that contains only pages with problems (Missing, Mismatch, Chained, or Error), and a Copy Missing button that copies all URLs with no canonical tag directly to your clipboard.
Does the tool support HTTP and HTTPS URLs?
Yes. The Bulk Canonical Checker accepts both HTTP and HTTPS URLs. If you paste a URL without a protocol — for example example.com/page — the tool automatically prepends https:// before checking.
Should every page have a canonical tag?
Yes, as a best practice every public-facing HTML page should include a canonical tag. For the primary version of a page, it should be a self-referencing canonical. For pages that are duplicates, paginated sequences, or print versions, the canonical should point to the original or first-page URL. Google's own documentation recommends explicitly declaring canonicals rather than leaving it to the search engine to guess.