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Canonical Header Checker

Audits pages for conflicting canonical URL signals between HTML tags and HTTP Link headers

Source Download skill
Repository
thedaviddias/Front-End-Checklist
Stars
74,632
Licence
MIT
Files
2 files

What it does

This skill teaches an AI agent to check whether a web page's canonical URL is declared consistently. A canonical tag in the HTML and a canonical Link header in the HTTP response both tell search engines which version of a page is the main one. If they point to different URLs, search engines may ignore both, which can cause duplicate content and indexing problems. Once installed, the agent compares the two signals, suggests a fix, and recommends checking the final rendered output rather than only source files.

Great for

  • Front-end or web developers preparing a site for search engine indexing
  • SEO specialists auditing metadata and crawlability on existing pages
  • Teams reviewing templates or routes that generate canonical tags

Skip it if

  • Sites that do not use canonical tags or Link headers, since the rule would not apply
  • Non-technical users who need a fully automated SEO audit, because the skill gives guidance and review steps but does not itself crawl a site or report scores
  • Sensitive or private sites where pages must not be fetched, because verification requires requesting the live page and its headers

Try asking

  • “Check whether the canonical tag on my product page matches the Link header the server sends”
  • “Review our Next.js metadata templates for canonical URL conflicts”
  • “Explain to my team why conflicting canonical signals hurt indexing and how to fix them”
  • “Verify the final rendered HTML and response headers for our blog routes”
Step-by-step guide: how to use Canonical Header CheckerInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 2 original files, the MIT licence and an attribution note.

    canonical-header.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip canonical-header.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip canonical-header.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Give the agent specific URLs or route/template files so it can compare real output rather than general advice.
  • Ask it to check the rendered HTML and HTTP headers together, since the skill recommends verifying final output.
  • Consult references/rule.md for framework-specific implementation details before applying changes.

What's inside

  • references/rule.md
  • SKILL.md

Redistributed unmodified from thedaviddias/Front-End-Checklist under the MIT licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.