Who blocks AI · #121 in the Majestic Million

robots.txt · checked 9 Nov 2026

Does cdc.gov block AI crawlers?

No. cdc.gov’s robots.txt lets all 19 AI crawlers we track crawl the site. Search engines such as Googlebot and Bingbot may crawl it.

GPTBotAllowed OAI-SearchBotAllowed ClaudeBotAllowed PerplexityBotAllowed Google-ExtendedAllowed CCBotAllowed

robots.txt: www.cdc.gov/robots.txt · 59 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	Allowed	no rule matches the home page
`ClaudeBot`	Anthropic	Allowed	no rule matches the home page
`Google-Extended`	Google	Allowed	no rule matches the home page
`CCBot`	Common Crawl	Allowed	no rule matches the home page
`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	Allowed	no rule matches the home page
`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.cdc.gov/robots.txt · 59 lines

1# Ignore FrontPage files

2User-agent: *

3Disallow: /_borders

4Disallow: /_derived

5Disallow: /_fpclass

6Disallow: /_overlay

7Disallow: /_private

8Disallow: /_themes

9Disallow: /_vti_bin

10Disallow: /_vti_cnf

11Disallow: /_vti_log

12Disallow: /_vti_map

13Disallow: /_vti_pvt

14Disallow: /_vti_txt

16# Do not index the following URLs

17Disallow: /travel/

18Disallow: /flu/espanol/

19Disallow: /migration/

20Disallow: /Features/SpinaBifidaProgram/

21Disallow: /concussion/HeadsUp/training/

22Disallow: /niosh/archive/

23Disallow: /TemplatePackage/examples

24Disallow: /TemplatePackage/gadgets

25Disallow: /TemplatePackage/modules

26Disallow: /TemplatePackage/subtopic

27Disallow: /TemplatePackage/Templates

28Disallow: /TemplatePackage/3.0/examples

29Disallow: /TemplatePackage/3.0/Templates

30Disallow: /TemplatePackage/4.0/docs

31Disallow: /TemplatePackage/4.0/gallery-internal

32Disallow: /templatepackage/examples

33Disallow: /templatepackage/gadgets

34Disallow: /templatepackage/modules

35Disallow: /templatepackage/subtopic

36Disallow: /templatepackage/Templates

37Disallow: /templatepackage/templates

38Disallow: /templatepackage/3.0/examples

39Disallow: /templatepackage/3.0/Templates

40Disallow: /templatepackage/3.0/templates

41Disallow: /templatepackage/4.0/docs

42Disallow: /templatepackage/4.0/gallery-internal

43Disallow: /templatepackage/dmat

45# Rover is a bad dog

46User-agent: Roverbot

47Disallow: /

49# EmailSiphon is a hunter/gatherer which extracts email addresses for spam-mailers to use

50User-agent: EmailSiphon

51Disallow: /

53# Exclude MindSpider since it appears to be ill-behaved

54User-agent: MindSpider

55Disallow: /

57# Sitemap link per CR14586

58Sitemap: https://www.cdc.gov/wcms-auto-sitemap-index.xml

What do the bots actually get?

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

History

19 October 2026: first checked.

Questions

Does cdc.gov block GPTBot?

No. cdc.gov’s robots.txt lets GPTBot crawl the site. GPTBot is OpenAI’s crawler for training data; blocking it doesn’t affect ChatGPT search, which uses OAI-SearchBot. Checked 9 November 2026.

Does cdc.gov block ClaudeBot?

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

Does cdc.gov block Google-Extended?

No. cdc.gov’s robots.txt lets Google-Extended crawl the site. 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 cdc.gov block PerplexityBot?

No. cdc.gov’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 cdc.gov?

Yes. cdc.gov’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.