Canonicalization Checker
Free, no signup. Check the canonical Google can see, the HTTP Link header, and whether the chosen target is actually a clean, live URL.
Checks run from our server; we fetch the URL you enter and don't keep the results. The URL and its canonical target are fetched to build this report. The full URL is not stored; after a successful check, only its domain may be remembered in this browser. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.
Example result
Illustrative example — fixed signals, not a live URL claim
Page checked: https://example.com/product?color=blue
This example assumes the canonical target returns a direct 200. If it redirected or failed, the same engine would add a high-risk finding instead of hiding that evidence.
How to use it
- Enter the exact URL variant you want to audit, including parameters when they are part of the question.
- Choose Audit canonical. The report shows every HTML and HTTP Link-header canonical observed.
- Read the override-risk explanations and fixes, then confirm that the target resolves directly to a live page.
- Use Search Console URL Inspection to compare the user-declared and Google-selected canonical for a verified property.
+ saves the current site or page. Use ☆ beside any saved site, page, or list to favorite it. Recent check history appears below.
Create a named list
Target filled from your local choices.
Site passport Local context for this saved site
Local data
Saved targets, named lists, and recent check summaries remain only in this browser.
Observed canonical signals
Google override-risk predictor
This is a deterministic signal check, not a claim about Google’s indexed canonical.
Why these verdicts and how to verify them
Portable baseline
Download this result as JSON, then import it after a later run of the exact same URL. The baseline stays in your files and is not uploaded.
Rate this tool
What the results mean
The report checks the observable signals involved in CanonicalizationHow search engines pick one canonical URL among duplicates and consolidate signals onto it. and estimates when conflicts may lead Google to select another URL.
- High marks a direct conflict such as disagreeing canonicals, noindex plus canonical, an unreachable target, or a target that redirects.
- Medium marks a meaningful consistency risk, including cross-domain targets or hreflang that omits the canonical URL.
- Low means the observed signals are internally consistent or describe a normal parameter cleanup. It is not a promise that Google agrees.
How it works
One bounded server request collects the final URL, response headers, and HTML body. A deterministic parser reads canonical and hreflang links from the head plus canonical Link headers, resolves relative URLs, records duplicates and noindex, and then checks each unique canonical target through the status endpoint. The predictor maps those observed signals to explicit risk reasons and fixes.
Features
- HTML and HTTP Link-header canonical discovery.
- Relative, missing, multiple, and conflicting canonical checks.
- Noindex, hreflang, cross-host, protocol, and parameter consistency signals.
- Bounded canonical-target status and redirect verification.
- Plain-language likelihood labels without claiming Google's selection.
Limitations
The checker reads the server response and does not render JavaScript. It cannot compare page content across duplicate URLs, inspect all internal links or sitemap signals, access Search Console, or observe Google's selected canonical. A low-risk result only describes the evidence fetched in this run.
Frequently asked questions
Can this tell me Google’s selected canonical?
No. Google’s selected canonical is only observable through Search Console URL Inspection for a verified property. This tool predicts override risk from observable HTTP and HTML signals.
Does it fetch rendered JavaScript canonicals?
No. It reads the server response. A canonical injected only after JavaScript runs is discouraged and should be verified in URL Inspection.
Should every indexable page have a self-referencing canonical?
A self-referencing canonical is generally useful because it makes the preferred URL explicit and helps keep parameters or alternate URL forms from becoming ambiguous. It is still a hint, not a directive.
Can a canonical point to a redirect?
It can, but it creates a conflicting and inefficient signal path. Point the canonical directly to the final live 200 URL and align internal links, redirects, and sitemap entries with it.
Why might Google ignore a canonical tag?
Google may choose another URL when content, redirects, internal links, sitemaps, hreflang, protocol or host signals disagree, or when the declared target is unavailable. This checker tests several observable conflicts but cannot see Google’s full index-level evidence.
Feature requests for Canonical Checker
Upvote what you want most. New ideas can be submitted from the floating Feedback menu; requests appear here once approved, and the most-wanted rise to the top.
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ツールについて
HTMLとHTTPのcanonicalシグナルを監査し、canonical対象を確認して、Googleが別のcanonical URLを選ぶ原因になり得るシグナルを証拠に基づいて説明します。
機能
- HTMLとHTTP Linkヘッダーからcanonicalを検出します。相対・欠落・複数・競合canonicalを確認します。noindex、hreflang、別ホスト、プロトコル、パラメータの整合性を調べます。canonical対象のステータスとリダイレクトを制限付きで検証します。Googleの選択を断定せず、平易な可能性ラベルを示します。
仕組み
仕組み：制限付きのサーバーリクエスト1回で最終URL、レスポンスヘッダー、HTML本文を取得します。決定論的パーサーがhead内のcanonical・hreflangリンクとcanonical Linkヘッダーを読み取り、相対URLを解決し、重複とnoindexを記録します。その後、一意なcanonical対象ごとにステータスエンドポイントで確認します。予測は観測したシグナルを明示的なリスク理由と修正方法へ対応付けます。
制限事項
- 制限：チェッカーはサーバーレスポンスを読み取るだけで、JavaScriptをレンダリングしません。重複URL間のページ内容、すべての内部リンクやサイトマップシグナル、Search Console、Googleが選択したcanonicalは確認できません。低リスク結果は、この実行で取得した証拠だけを説明します。
よくある質問
Googleがcanonicalタグを無視するのはなぜですか？
コンテンツ、リダイレクト、内部リンク、サイトマップ、hreflang、プロトコル、ホストのシグナルが一致しない場合や、宣言した対象が利用できない場合、Googleは別のURLを選ぶことがあります。このチェッカーは観測可能ないくつかの競合を確認しますが、Googleのインデックス全体の証拠は見られません。
レンダリング後のJavaScript canonicalを取得しますか？
いいえ。サーバーレスポンスを読み取ります。JavaScript実行後にだけ挿入されるcanonicalは推奨されないため、URL Inspectionで確認してください。
Googleが選択したcanonicalを確認できますか？
いいえ。検証済みプロパティでGoogleが選択したcanonicalを確認できるのはSearch Console URL Inspectionだけです。このツールは観測可能なHTTPとHTMLシグナルから上書きリスクを予測します。
インデックス登録可能なすべてのページに自己参照canonicalが必要ですか？
自己参照canonicalは優先URLを明示し、パラメータや別形式URLの曖昧さを減らすため一般に有用です。ただし、あくまでヒントであり、ディレクティブではありません。
canonicalをリダイレクト先に指定できますか？
指定できますが、競合して非効率なシグナル経路になります。canonicalは最終的な稼働中の200 URLへ直接向け、内部リンク、リダイレクト、サイトマップの登録も揃えてください。