Set a canonical URL for a PDF or other non-HTML file using the HTTP Link header
domain: developers.google.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Identify non-HTML resources (PDF, Word doc, etc.) that duplicate content available at an HTML URL
Configure your server/CDN to return a Link response header formatted as Link: <https://example.com/page>; rel="canonical" on requests for the non-HTML resource
Use an absolute URL in the header value, matching the same rule as the HTML rel=canonical link element
Verify the header renders correctly using a raw HTTP request (e.g. curl -I) rather than a browser, since it isn't visible in rendered HTML
Avoid also adding a conflicting rel=canonical link element for the same resource that points elsewhere
Known gotchas
Google documents this method as honored for Search results specifically, not necessarily by every consumer of the resource
Setting both an HTTP header canonical and a conflicting in-document canonical is more error-prone than picking one method
This only works for resources you control at the server/edge level; static file hosts without custom header support can't implement it directly
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