Does the canonical tag really prevent your pages from being indexed?

What's the difference between canonicalization and indexation?

This is the central point of this statement: canonicalization and indexation are two distinct processes. Indexation determines whether a page enters Google's index. Canonicalization comes after, to choose which version to display when multiple URLs present similar or identical content.

Concretely — a page can be indexed even if you mark it as canonical to another URL. Google keeps both versions in its index, but only displays one in the SERPs. The canonical tag is a recommendation, not a blocking instruction.

How does Google select the canonical URL?

Martin Splitt clarifies that Google examines two main elements: your recommendation via the canonical tag, and how URLs are linked elsewhere on the web. If your backlinks point massively to URL A while you declare B as canonical, Google may ignore your preference.

Shorter URLs are preferable but not mandatory. This is a weak signal among others — not a decisive criterion. If your URL is 150 characters long but receives all the links, it can become the de facto canonical.

Does rendering mode influence this process?

No. Whether your site uses server-side rendering or client-side rendering, the canonicalization logic remains identical. Google treats the canonical tag the same way regardless of the HTML generation method.

This clarification likely addresses a recurring confusion: some believed that JavaScript applications risked having their canonicals ignored or misinterpreted. This is not the case.

• Canonicalization does not block indexation — the two processes are independent
• Google combines your canonical tag with external signals (links, mentions) to choose the displayed version
• Shorter URLs are a weak signal, not an eliminating criterion
• Server-side and client-side rendering: no difference in canonical treatment

Does this statement match what we observe in the field?

Yes and no. In principle, it's correct: we regularly see URLs indexed despite a canonical tag pointing elsewhere. But Splitt's wording masks an inconvenient reality — many SEO professionals still confuse canonical with noindex because Google itself has long maintained this confusion.

For years, we've observed cases where Google de facto disindexed pages marked canonical to another URL. Not systematically, but often enough to create confusion. This statement finally clarifies the theoretical model, but guarantees nothing about the algorithm's actual behavior in edge cases.

What gray areas remain in this assertion?

Splitt says Google "examines the owner's recommendation via the canonical tag and how the URL is linked elsewhere on the web." Fine. But what is the relative weight of each signal? [To verify] — we don't know if a backlink accounts for 10%, 50%, or 80% of the decision.

Second gray area: "shorter URLs are preferable but not mandatory." Preferable to what extent? If two URLs are strictly equivalent on all other criteria, does the shorter URL win every time? And if so, what difference in length triggers a switch? [To verify] — no numerical data.

In what cases does this rule not apply?

If you massively canonicalize pages to a URL that has no thematic relationship, Google may outright ignore your tags. Same if you create chains of canonicals (A → B → C) — Google hates this and will choose arbitrarily.

Another problematic case: sites with infinite pagination in JavaScript. Technically, client-side rendering changes nothing according to Splitt. In practice, if Google doesn't crawl your paginated pages correctly, your canonicals may point to nothing. Theory and reality don't always align.

What should you do concretely with your canonical tags?

First, audit your existing canonicals. Verify that they always point to accessible, indexable, and relevant URLs. A canonical pointing to a 404 or a page blocked by robots.txt is a contradictory signal that Google may ignore.

Next, align your internal linking with your canonicalization choices. If you declare A as canonical, have your internal links point to A, not B. Google considers overall consistency — if you say one thing and do the opposite, you weaken your recommendation.

What mistakes should you absolutely avoid?

Never create chains of canonicals. Each URL should point directly to the final canonical version, with no intermediary. Google follows one or two jumps maximum, after which it abandons or chooses arbitrarily.

Also avoid canonicalizing pages with substantially different content. The tag is meant to manage duplicates or near-duplicates, not to merge distinct pages. If you force canonicalization between two different contents, Google may ignore your directive and index both versions anyway.

• Verify that all your canonicals point to 200 OK and indexable URLs
• Align your internal linking: links should point to the declared canonical version
• Remove canonical chains — each URL should point directly to the final one
• Reserve canonicals for actual duplicates, not pages with distinct content
• If you want to block indexation, use noindex, never canonical alone
• Audit regularly: Google may ignore your canonicals if external signals (backlinks) contradict your choice

How can you ensure Google respects your preferences?

Use Search Console to check which URL Google has actually chosen as canonical. In the URL inspection tool, the "Coverage" section indicates the canonical URL selected by Google. If it differs from your declaration, that's a warning sign.

Strengthen your canonicals with 301 redirects when possible. If you have no reason to keep multiple versions accessible, redirect the variants to the canonical. This is the strongest signal — far better than an HTML tag.