Search crawlers vs SEO crawlers
Search-engine crawlers like Googlebot and Bingbot build the indexes that determine search visibility. Third-party SEO crawlers like AhrefsBot and SemrushBot feed analysis tools and do not affect rankings directly. Distinguishing them matters for crawl-budget reasoning and for deciding what to allow or limit.
The core difference
A search-engine crawler builds an index that determines whether and how your pages appear in that engine's results. Googlebot, Bingbot, YandexBot, and similar are in this group: allowing them is how you become findable in those engines.
A third-party SEO crawler, such as AhrefsBot or SemrushBot, gathers data for an analysis product. It indexes your site so that tool's users can study backlinks, keywords, or competitors. Crucially, its crawling does not feed any search engine and does not change your rankings.
- Search crawlers: build engine indexes that affect visibility
- SEO crawlers: feed third-party tools, do not change rankings
- Both are bots, but only one group affects search results
Why it changes your decisions
The distinction drives policy. Blocking a search-engine crawler can remove you from that engine — a serious visibility cost. Blocking or rate-limiting a third-party SEO crawler only affects that tool's dataset, which may be acceptable or even desirable if the crawler is consuming significant resources.
It also affects crawl-budget reasoning: heavy third-party SEO crawling can load your server without any indexing benefit. Knowing which is which lets you protect capacity for the crawlers that actually matter to visibility.
How it appears in analytics and logs
Seeing Googlebot or Bingbot means an engine that affects your visibility is crawling you. Seeing AhrefsBot, SemrushBot, or similar means a third-party tool is indexing you for its own product — useful or not to you, but not a ranking input.
Diagnostic use case
Decide which crawlers genuinely affect your search visibility versus which are third-party tools, so you can allow, limit, or block each appropriately.
What WebmasterID can help detect
WebmasterID classifies crawlers server-side into search engines versus third-party SEO tools, so you can see which crawl traffic affects visibility and which is tool-driven, without parsing user agents yourself.
Common mistakes
- Assuming any bot labelled a crawler affects Google or Bing rankings.
- Blocking a search-engine crawler while meaning to block a third-party tool.
- Ignoring third-party crawler load because it has no indexing value.
Privacy and accuracy notes
This distinction is about crawler purpose, not human identity — every crawler here is a bot, not a person. WebmasterID records all of them as bot events, separate from human analytics.
Related pages
- AhrefsBot — Ahrefs SEO crawler
AhrefsBot is the crawler operated by Ahrefs to build its SEO and backlink index. It is a third-party crawler, not a search engine, so it does not affect Google or Bing rankings directly. It uses the AhrefsBot robots.txt token and is documented as respecting robots.txt and crawl-delay.
- Managing third-party SEO crawler load
Third-party SEO crawlers such as AhrefsBot and SemrushBot can generate significant request volume without contributing to search visibility. You can manage their load by targeting their tokens in robots.txt, using crawl-delay where the crawler supports it, and blocking those that bring no value to you.
- Bot vs human
Separate automated crawlers from real human visits.
Sources and verification notes
- Google — Google crawlers (user agents) overviewReference for search-engine crawler identities versus third-party tools.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.