Canonical Tag

Handles canonical URL setup to fix duplicate content issues and tell search engines which version of a page you want indexed. You'd reach for this when dealing with HTTPS vs HTTP variants, www vs non-www, trailing slashes, or pagination and parameter URLs that create duplicates. Covers both 301 redirects (the strongest signal, use when you can) and canonical tags (for when redirects aren't practical). Includes Next.js metadata patterns and server config snippets for Apache and Nginx. The guidance on avoiding canonical chains and keeping sitemap URLs aligned with canonicals is solid. Works alongside the hreflang and sitemap skills for complete technical SEO coverage.

skills.sh installs: 1.2K
GitHub stars: 1.1K
last updated: Aug 21, 2026

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Install

$ npx -y skills add kostja94/marketing-skills --skill canonical-tag --agent claude-code

Installs into .claude/skills of the current project.

Files

SEO Technical: Canonicalization

Determine the preferred URL for each page identity, consolidate duplicate variants, and verify that redirects, canonical annotations, internal links, sitemaps, and localization signals agree.

Scope

Treat these as one duplicate-page canonicalization problem when they expose the same or substantially similar primary content:

HTTP and HTTPS;
www and non-www hosts, including combined protocol/host variants;
trailing-slash and non-trailing-slash paths;
repeated path slashes such as /docs//guide;
directory defaults such as /docs/ and /docs/index.html;
historical extensions such as /guide.html and /guide;
case variants such as /Guide and /guide;
UTM and other tracking parameters that do not change primary content.

Do not assume that similar-looking URLs are duplicates. Case, parameters, extensions, and slash behavior can identify different resources. Compare response behavior, primary content, and project intent before consolidating.