Glossary · Crawlers and access
delivery comparison
Fetching the same URL as each named crawler identity and as an unnamed browser control within the same second, then comparing status, redirect target and word count.
What delivery comparison means
Fetching the same URL as each named crawler identity and as an unnamed browser control within the same second, then comparing status, redirect target and word count. It shows whether the site treats a crawler's name differently from a person; it cannot show whether the real crawler, arriving from its own address range, is treated the same way.
What delivery comparison can and cannot support
| It can support | It cannot support |
|---|---|
| Fetching the same URL as each named crawler identity and as an unnamed browser control within the same second, then comparing status, redirect target and word count. | It shows whether the site treats a crawler's name differently from a person; it cannot show whether the real crawler, arriving from its own address range, is treated the same way. |
How CrawlCheck measures delivery comparison
3 finding codes in the scanner read this. The share of all scans carrying each is computed from the live corpus when this page is served, not typed into it.
| Finding code | Share of scans | Guide |
|---|---|---|
CRAWLER_SERVED_LESS | 0.5% | Do AI crawlers render JavaScript? |
CRAWLER_REDIRECTED_AWAY | 0.1% | Crawler delivery: refused, redirected away, or served less |
ANSWER_ENGINE_REFUSED | 3.5% | Is Cloudflare blocking AI crawlers on your site? What changes on 15 September 2026 |
Every code, its rule and its current rate: the dataset page. Scan a site to see which apply to it.
Where delivery comparison comes up on this site
- Eight contradictions in our own copy, rechecked todayIt does not: the delivery comparison fetches the homepage as fifteen identities, twelve of them the user-agent strings of named crawlers, because that is the measurement.
Terms this definition uses
Related terms in Crawlers and access
Who is fetching, whether they are who they claim, and what your rules actually permit.
retrieval crawler · user-triggered fetch · verified crawler · forged crawler identity · unverifiable · robots.txt · user-agent group · AI opt-out · Content-Signal · crawl budget · cloaking · challenge page at 200 · uniform refusal · nonexistent-path control · blocked render resource · off-host redirect · homepage refused · FCrDNS · Crawler trap · Conditional request · ASN blocking · operator feed · residential proxy · Google-Extended · Google-Agent · GPTBot vs OAI-SearchBot · ClaudeBot vs Claude-User · PerplexityBot vs Perplexity-User · CCBot · Bytespider · agentic traffic · crawler classification · user agent · datacenter IP · vantage point · rate limit · honeypot
Questions about delivery comparison
What is delivery comparison?
Fetching the same URL as each named crawler identity and as an unnamed browser control within the same second, then comparing status, redirect target and word count.
What does delivery comparison not show or guarantee?
It shows whether the site treats a crawler's name differently from a person; it cannot show whether the real crawler, arriving from its own address range, is treated the same way.
How does CrawlCheck measure delivery comparison?
Through the finding codes CRAWLER_SERVED_LESS, CRAWLER_REDIRECTED_AWAY, ANSWER_ENGINE_REFUSED, each with a stated rule, evidence bytes and a live share of scans on the dataset page.
Which area of the glossary does delivery comparison belong to?
Crawlers and access: Who is fetching, whether they are who they claim, and what your rules actually permit.
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See it in the full glossary · 668 terms across 19 areas.