Who blocks AI · #1103 in the Majestic Million

robots.txt · checked 9 Nov 2026

Does worldcat.org block AI crawlers?

Yes. worldcat.org’s robots.txt blocks 4 of the 19 AI crawlers we track, including GPTBot, Google-Extended, CCBot and ChatGPT-User. Search engines such as Googlebot and Bingbot may crawl it.

GPTBotBlocked OAI-SearchBotAllowed ClaudeBotAllowed PerplexityBotAllowed Google-ExtendedBlocked CCBotBlocked

robots.txt: search.worldcat.org/robots.txt · 32 lines
llms.txt: none
Checked: 9 November 2026, as canaicrawl. We check again every week.

Every bot, and the line that decides

Search engines

Bot	Operator	robots.txt	Deciding line
`Googlebot`	Google	Allowed	no rule matches the home page
`Bingbot`	Microsoft	Allowed	no rule matches the home page
`DuckDuckBot`	DuckDuckGo	Allowed	no rule matches the home page
`Applebot`	Apple	Allowed	no rule matches the home page
`PetalBot`	Huawei	Allowed	no rule matches the home page
`YandexBot`	Yandex	Allowed	no rule matches the home page
`Baiduspider`	Baidu	Allowed	no rule matches the home page

AI search

Bot	Operator	robots.txt	Deciding line
`OAI-SearchBot`	OpenAI	Allowed	no rule matches the home page
`PerplexityBot`	Perplexity	Allowed	no rule matches the home page
`Claude-SearchBot`	Anthropic	Allowed	no rule matches the home page
`DuckAssistBot`	DuckDuckGo	Allowed	no rule matches the home page
`Amazonbot`	Amazon	Allowed	no rule matches the home page
`YouBot`	You.com	Allowed	no rule matches the home page

AI training

Bot	Operator	robots.txt	Deciding line
`GPTBot`	OpenAI	Blocked	line 2 · `Disallow: /` under `User-agent: GPTBot`
`ClaudeBot`	Anthropic	Allowed	no rule matches the home page
`Google-Extended`	Google	Blocked	line 10 · `Disallow: /` under `User-agent: Google-Extended`
`CCBot`	Common Crawl	Blocked	line 14 · `Disallow: /` under `User-agent: CCBot`
`Applebot-Extended`	Apple	Allowed	no rule matches the home page
`GoogleOther`	Google	Allowed	no rule matches the home page
`Meta-ExternalAgent`	Meta	Allowed	no rule matches the home page
`Bytespider`	ByteDance	Allowed	no rule matches the home page

User-triggered fetchers

Bot	Operator	robots.txt	Deciding line
`ChatGPT-User`	OpenAI	Blocked	line 6 · `Disallow: /` under `User-agent: ChatGPT-User`
`Claude-User`	Anthropic	Allowed	no rule matches the home page
`Perplexity-User`	Perplexity	Allowed	no rule matches the home page
`MistralAI-User`	Mistral	Allowed	no rule matches the home page
`Meta-ExternalFetcher`	Meta	Allowed	no rule matches the home page

SEO tools

Bot	Operator	robots.txt	Deciding line
`AhrefsBot`	Ahrefs	Allowed	no rule matches the home page
`SemrushBot`	Semrush	Allowed	no rule matches the home page
`MJ12bot`	Majestic	Allowed	no rule matches the home page
`DotBot`	Moz	Allowed	no rule matches the home page

View search.worldcat.org/robots.txt · 32 lines

1User-agent: GPTBot

2Disallow: /

4# No ChatGPT user allowed anywhere on the site

5User-agent: ChatGPT-User

6Disallow: /

8# No Google Bard allowed anywhere on the site

9User-agent: Google-Extended

10Disallow: /

12# No Common Crawl Bot

13User-agent: CCBot

14Disallow: /

16User-agent: *

17Crawl-delay: 5

18Disallow: /search

19Disallow: /libraries/search

20Disallow: /lists/search

21Disallow: /user/account

22Disallow: /user/lists

23Disallow: /user/libraries

24Disallow: /libraries

25Disallow: /arcviewer

26Disallow: /registry

27Disallow: /formats-editions/*

28Disallow: /search?q=*

29Disallow: /libraries/search?q=*

30Disallow: /lists/search?q=*

32Sitemap: https://search.worldcat.org/sitemap.xml

What do the bots actually get?

This page reads robots.txt, which states what worldcat.org asks of crawlers. A firewall or CDN can still refuse a bot that robots.txt allows. The live check requests the page as each bot and shows the status it gets.

Run a live check on worldcat.org Test a path in the robots.txt tester

History

19 October 2026: first checked.

Questions

Does worldcat.org block GPTBot?

Yes. worldcat.org’s robots.txt disallows GPTBot from the whole site (line 2: Disallow: /). GPTBot is OpenAI’s crawler for training data; blocking it doesn’t affect ChatGPT search, which uses OAI-SearchBot. Checked 9 November 2026.

Does worldcat.org block ClaudeBot?

No. worldcat.org’s robots.txt lets ClaudeBot crawl the site. ClaudeBot is Anthropic’s crawler for training data. Checked 9 November 2026.

Does worldcat.org block Google-Extended?

Yes. worldcat.org’s robots.txt disallows Google-Extended from the whole site (line 10: Disallow: /). Google-Extended is the token that controls whether Google may use pages for Gemini training and grounding; it doesn’t affect Google Search. Checked 9 November 2026.

Does worldcat.org block PerplexityBot?

No. worldcat.org’s robots.txt lets PerplexityBot crawl the site. PerplexityBot is the crawler that indexes pages for Perplexity’s answers. Checked 9 November 2026.

Can ChatGPT search find worldcat.org?

Yes. worldcat.org’s robots.txt lets OAI-SearchBot crawl the site. OAI-SearchBot is the crawler behind ChatGPT search; blocking it keeps the site out of ChatGPT’s search answers. Checked 9 November 2026.