Who blocks AI · #482 in the Majestic Million

robots.txt · checked 9 Nov 2026

Does science.org block AI crawlers?

Yes. science.org’s robots.txt blocks 5 of the 19 AI crawlers we track, including GPTBot, Google-Extended, CCBot and 2 more. Search engines such as Googlebot and Bingbot may crawl it.

GPTBotBlocked OAI-SearchBotAllowed ClaudeBotAllowed PerplexityBotAllowed Google-ExtendedBlocked CCBotBlocked

robots.txt: www.science.org/robots.txt · 51 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 37 · `Disallow: /` under `User-agent: GPTBot`
`ClaudeBot`	Anthropic	Allowed	no rule matches the home page
`Google-Extended`	Google	Blocked	line 28 · `Disallow: /` under `User-agent: Google-Extended`
`CCBot`	Common Crawl	Blocked	line 46 · `Disallow: /` under `User-agent: CCBot`
`Applebot-Extended`	Apple	Blocked	line 49 · `Disallow: /` under `User-agent: Applebot-Extended`
`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 43 · `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 www.science.org/robots.txt · 51 lines

1Sitemap: https://www.science.org/sitemap_index.xml

2Sitemap: https://www.science.org/sitemap-index-1.txt

3User-agent: *

4Disallow: /action

5Disallow: /help

6Disallow: /search

7Disallow: /feedback

8Disallow: /page/account-confirmation-thanks

9Disallow: /media

10Disallow: /medical-research

11Disallow: /servlet/linkout

12Disallow: /na101/

13Disallow: /na101v1/

14Disallow: /na102/

15Disallow: /doi/mlt/

16Disallow: /pb/widgets

17Disallow: /author

18Allow: /action/showFeed

19Allow: /action/showJournal

20Allow: /action/showPublications

21Allow: /action/showXml

22Allow: /action/showTopic

23Allow: /action/showBook

24Allow: /action/showCoverImage

25Allow: /action/downloadSupplement

27User-agent: Google-Extended

28Disallow: /

30User-agent: anthropic-ai

31Disallow: /

33User-agent: Twitterbot

34Allow: /

36User-agent: GPTBot

37Disallow: /

39User-agent: GPTBot

40Disallow: /

42User-agent: ChatGPT-User

43Disallow: /

45User-agent: CCBot

46Disallow: /

48User-agent: Applebot-Extended

49Disallow: /

What do the bots actually get?

This page reads robots.txt, which states what science.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 science.org Test a path in the robots.txt tester

History

19 October 2026: first checked.

Questions

Does science.org block GPTBot?

Yes. science.org’s robots.txt disallows GPTBot from the whole site (line 37: 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 science.org block ClaudeBot?

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

Does science.org block Google-Extended?

Yes. science.org’s robots.txt disallows Google-Extended from the whole site (line 28: 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 science.org block PerplexityBot?

No. science.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 science.org?

Yes. science.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.