tech

How to fix: <link rel=canonical> present

Why this matters

When the same content is reachable via multiple URLs (trailing slash, query parameters, www vs. apex), <link rel="canonical"> tells crawlers which is the real version and prevents duplicate-content dilution.

Background

A canonical link tag tells search engines which URL to index when the same content is reachable at multiple addresses (http vs https, www vs apex, query-string variants). Without it, ranking is split across duplicates and the wrong URL might win — losing the SEO benefit of every backlink.

References

Google Search Central · technical SEO baseline

How to fix

Code snippet for each stack we cover. Pick the one matching your server / framework.

nginx

Set the canonical at the application layer — nginx can rewrite URLs to a single canonical though.

apache

Same — Rewrite to a single canonical.

cloudflare

Cloudflare Workers / Transform Rules can normalise host (www → apex or vice versa).

wordpress

Yoast / RankMath / All-in-One SEO all add canonical tags automatically.

flask

<link rel="canonical" href="https://your-site.com/canonical-path"> in your base template.

express

Same — render the canonical in your HTML template.

rails

<%= tag.link rel: 'canonical', href: canonical_url %>

Verify it's working

View source. <link rel="canonical"> should be present in <head> and point to the preferred URL.

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