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Official statement

Nofollow, sponsored, and UGC attributes generally prevent the transfer of signals but do not ensure that Google won’t crawl the link. To fully block crawling, use robots.txt. An intermediate solution consists of redirecting these links through a directory blocked in robots.txt.
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Extracted from a Google Search Central video

⏱ 55:06 💬 EN 📅 14/08/2020 ✂ 17 statements
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📅
Official statement from (5 years ago)
TL;DR

The nofollow, sponsored, and UGC attributes block the transfer of signals (PageRank, anchors) but do not guarantee that Google will ignore the link during crawling. To completely prevent Googlebot from following a URL, robots.txt remains the go-to tool. A hybrid technique involves redirecting these links to a directory blocked by robots.txt, providing granular control of crawl budget without polluting the directives file.

What you need to understand

What’s the difference between blocking signals and blocking crawling?

When you add rel="nofollow" (or its variants sponsored/UGC) to a link, you are asking Google not to transfer PageRank or use the anchor text as a relevance signal. It’s a directive about signal handling, not a crawling instruction.

But here’s the catch: Googlebot can still discover and crawl the target URL. The bot explores the web opportunistically — it sees a URL, it notes it, and based on its schedule, it may decide to visit it. Nofollow is not a technical lock that physically denies access.

Why does this nuance cause practical problems?

Because many SEOs believe that nofollow = URL invisible to Google. The result: pages thought to be off-radar end up indexed, consuming crawl budget, or revealing URL structures that we preferred to keep private.

Specifically? If you apply nofollow to links leading to facet filters, sort pages, or session URLs, Google can still crawl them. You save PageRank, sure, but you do not protect your technical architecture.

How can you actually block a link from being crawled?

The official method: robots.txt. You declare a directory or URL pattern as Disallow, and Googlebot will respect this directive (except for rare exceptions, like URLs already indexed with strong external backlinks).

Google also suggests a clever intermediate approach — redirecting your “questionable” links to a path blocked by robots.txt (e.g., /blocked-crawl/). The HTML link remains clickable for users if needed, but the bot comes to an immediate halt. This is particularly useful for utility links (logout, filters, printable versions) where nofollow alone is not sufficient.

  • Nofollow/sponsored/UGC: blocks the transfer of signals (PageRank, anchors) but not crawling
  • Robots.txt: blocks crawling but does not prevent indexing if strong external backlinks exist
  • Redirecting to a blocked directory: hybrid solution for granular crawl control without polluting robots.txt
  • A nofollow link can still appear in server logs — it has been crawled even if not utilized for ranking
  • The choice between these methods depends on your goal: saving PageRank vs. protecting crawl budget vs. masking URLs

SEO Expert opinion

Is this statement consistent with field observations?

Absolutely. Server logs have confirmed this for years: we regularly see Googlebot crawling nofollow URLs, especially if they are present on high-crawl pages (homepage, main categories). Nofollow has never been a barrier to crawling — it’s just that many practitioners confused the two mechanisms.

The real question is why Google crawls these links despite the nofollow. Likely hypothesis: the bot wants to map the entire link graph to detect manipulation patterns, identify site networks, or simply discover new URLs before deciding whether to index them. Nofollow tells “don’t exploit this signal,” not “ignore this URL.”

Is the redirect technique risk-free?

On paper, redirecting to a directory blocked by robots.txt seems clean. In practice, it adds a layer of complexity — you create artificial 301/302 redirects, which can slow down the user experience if poorly implemented (think about logout links, for instance).

Another point: if you redirect to /blocked-crawl/ and then block that directory, Google will not crawl the final target… but it will still see the initial redirect. It remains in the logs as a crawl attempt. For pure crawl budget reasons, it’s effective. To completely mask a URL? Less certain. [To be checked]: the exact impact on crawl budget when thousands of links point to blocked redirects — Google could consider this noise.

When should you really care about this distinction?

Let’s be honest: for 80% of sites, the difference between nofollow and crawl blocking is negligible. If you have a WordPress blog with a few nofollow pages, Google may crawl them once a month. Nothing to panic about.

It becomes critical on large sites: e-commerce with millions of facets, UGC platforms with duplicate content, sites with infinite category trees. There, every unnecessary crawled URL = wasted budget. In these cases, combining nofollow (for signals) and robots.txt (for crawling) becomes a complete SEO architecture strategy.

Warning: blocking a URL with robots.txt does NOT prevent its indexing if it receives external backlinks. Google can index a page without crawling it, relying solely on anchor text and the context of incoming links. To de-index, a noindex tag is required… which it can only read if it crawls the page. Classic paradox — in this case, allowing crawling then applying noindex is the right strategy.

Practical impact and recommendations

What should you audit on your site right now?

First action: analyze your server logs or Search Console (Crawl report) to identify URLs crawled but marked as nofollow. You will probably discover that Google is visiting pages you thought were protected — sort filters, internal search result pages, session URLs.

Next, cross-check this data with your actual crawl budget (pages crawled per day vs. strategic pages). If you find that 30% of the crawl is going to non-priority URLs despite nofollow, that’s a signal to switch to robots.txt or the redirect technique.

How do you choose between nofollow, robots.txt, and blocked redirection?

Use the nofollow/sponsored/UGC attribute when your goal is to avoid passing on PageRank or to prevent a manual penalty (affiliate links, sponsored content, comments). It’s sufficient for Google compliance and signal management.

Switch to robots.txt if you want to save crawl budget on entire non-strategic sections (/admin/, /api/, /print/). This is the industrial solution for high volumes.

Reserve redirection to a blocked directory for hybrid cases: links that need to remain clickable for UX (e.g., logout, currency switch) but that you want to exclude from crawling entirely. This is a solution for SEO architects, not a patch to apply everywhere.

What errors should you absolutely avoid?

NEVER block an URL you want to de-index via robots.txt — Google won’t be able to read the noindex tag. It’s the most common pitfall, especially after a migration or a cleanup of duplicate content.

Avoid mixing nofollow and canonical on the same link. If A points to B with nofollow, but B canonicalizes to C, you create contradictory signals. Google will likely sort it out, but you lose clarity and control.

  • Audit server logs to identify URLs crawled despite nofollow
  • Ensure that robots.txt does not block pages with noindex tags (technical contradiction)
  • Test the redirect technique on a sample before mass deployment
  • Document your crawl strategy: which directories are nofollow, which ones are in robots.txt, and why
  • Monitor changes in crawl budget after adjustments (Search Console, Exploration Statistics report)
  • For sites with complex architecture, map out the paths of prioritized vs. secondary crawls
Fine management of crawl and link signals requires a deep understanding of Google mechanics and a thorough analysis of your log data. For high-volume sites or complex architecture, these optimizations can quickly become time-consuming and require precise technical arbitration. If you lack internal resources or want to secure your approach, consulting a specialized SEO agency allows you to benefit from a comprehensive audit of your crawl budget and a tailored blocking/nofollow strategy aligned with your business challenges. The investment is justified as soon as crawl waste impacts the indexing of your strategic pages.

❓ Frequently Asked Questions

Si je mets un lien en nofollow, Google peut-il quand même l'indexer ?
Oui. Le nofollow bloque la transmission de signaux (PageRank, ancres) mais n'empêche pas Google de crawler l'URL et potentiellement de l'indexer, surtout si elle reçoit des backlinks externes. Pour bloquer l'indexation, utilisez une balise noindex sur la page cible.
Quelle différence entre nofollow, sponsored et UGC au niveau du crawl ?
Aucune différence technique pour le crawl — les trois attributs sont traités de manière identique par Googlebot. Ils servent avant tout à qualifier la nature du lien (éditorial vs payant vs généré par les utilisateurs) pour aider Google à mieux interpréter le graphe de liens.
La technique de redirection vers répertoire bloqué ralentit-elle mon site ?
Potentiellement, si elle implique une redirection HTTP côté serveur pour chaque clic utilisateur. Pour des liens rarement cliqués (filtres, logout), l'impact UX est négligeable. Pour des liens fréquents, préférez robots.txt direct plutôt qu'ajouter une couche de redirection.
Puis-je bloquer par robots.txt une URL déjà indexée pour la faire disparaître de Google ?
Non, c'est contre-productif. Si vous bloquez le crawl, Google ne pourra pas lire la balise noindex nécessaire pour désindexer. Il faut d'abord laisser crawler avec noindex, attendre la désindexation, puis éventuellement bloquer par robots.txt.
Comment vérifier si Google crawle mes liens en nofollow ?
Consultez le rapport Statistiques sur l'exploration dans Search Console ou analysez vos logs serveur (Googlebot User-Agent). Vous verrez les URLs visitées par le bot, même si elles sont en nofollow. Croisez avec votre maillage interne pour identifier les écarts.
🏷 Related Topics
Crawl & Indexing AI & SEO Links & Backlinks

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Other SEO insights extracted from this same Google Search Central video · duration 55 min · published on 14/08/2020

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