cdc.gov: what it tells AI crawlers

On 27 October 2026, cdc.gov's robots.txt allowed all of GPTBot, OAI-SearchBot, ClaudeBot, Claude-SearchBot, Google-Extended, PerplexityBot and CCBot.

Last verified 2026-10-28 03:59 UTC (daily run of 2026-10-27). Proof for that day.

Panel: top 1k (Tranco)
robots.txt: ok (HTTP 200) · https://www.cdc.gov/robots.txt
unchanged since 2026-10-26 · sha256 2837016c20845bf0… · view as recorded
The * group: allows applies to every agent without its own group

Per AI bot, 2026-10-27

User agent	Verdict	How
GPTBot	allows	through the * group
OAI-SearchBot	allows	through the * group
ChatGPT-User	allows	through the * group
ClaudeBot	allows	through the * group
Claude-SearchBot	allows	through the * group
Claude-User	allows	through the * group
PerplexityBot	allows	through the * group
Perplexity-User	allows	through the * group
Googlebot	allows	through the * group
Google-Extended	allows	through the * group
Applebot-Extended	allows	through the * group
CCBot	allows	through the * group
Bytespider	allows	through the * group
Meta-ExternalAgent	allows	through the * group
Amazonbot	allows	through the * group

Other signals

Publishes /llms.txt	no
Publishes /ai.txt	no
Publishes /.well-known/tdmrep.json	no
Reserves TDM rights (TDMRep file, header or meta)	no
Declares Content Signals (robots.txt or header)	no
Says ai-train=no in a Content Signal	no
Points to an RSL licence (robots.txt License line or Link header)	no
Answers with an x402 payment offer (lower bound: only the homepage is probed)	no
Answers HTTP 402 Payment Required (lower bound: only the homepage is probed)	no
Sends noai / noimageai directives	no
Refused our fetcher (403 / challenge)	no

robots.txt as recorded sha256 74d7d0700f5b353a…

# Ignore FrontPage files
User-agent: *
Disallow: /_borders
Disallow: /_derived
Disallow: /_fpclass
Disallow: /_overlay
Disallow: /_private
Disallow: /_themes
Disallow: /_vti_bin
Disallow: /_vti_cnf
Disallow: /_vti_log
Disallow: /_vti_map
Disallow: /_vti_pvt
Disallow: /_vti_txt

# Do not index the following URLs
Disallow: /travel/
Disallow: /flu/espanol/
Disallow: /migration/
Disallow: /Features/SpinaBifidaProgram/
Disallow: /concussion/HeadsUp/training/
Disallow: /niosh/archive/
Disallow: /TemplatePackage/examples
Disallow: /TemplatePackage/gadgets
Disallow: /TemplatePackage/modules
Disallow: /TemplatePackage/subtopic
Disallow: /TemplatePackage/Templates
Disallow: /TemplatePackage/3.0/examples
Disallow: /TemplatePackage/3.0/Templates
Disallow: /TemplatePackage/4.0/docs
Disallow: /TemplatePackage/4.0/gallery-internal
Disallow: /templatepackage/examples
Disallow: /templatepackage/gadgets
Disallow: /templatepackage/modules
Disallow: /templatepackage/subtopic
Disallow: /templatepackage/Templates
Disallow: /templatepackage/templates
Disallow: /templatepackage/3.0/examples
Disallow: /templatepackage/3.0/Templates
Disallow: /templatepackage/3.0/templates
Disallow: /templatepackage/4.0/docs
Disallow: /templatepackage/4.0/gallery-internal

# Don't spider search pages
Disallow: /search.do

# Don't spider email-this-page pages
Disallow: /email.do
 
# Don't spider printer-friendly versions of pages
Disallow: /print.do

# Rover is a bad dog
User-agent: Roverbot
Disallow: /

# EmailSiphon is a hunter/gatherer which extracts email addresses for spam-mailers to use
User-agent: EmailSiphon
Disallow: /

# Exclude MindSpider since it appears to be ill-behaved
User-agent: MindSpider
Disallow: /

# Sitemap link per CR14586
Sitemap: http://www.cdc.gov/niosh/sitemaps/sitemapsNIOSH.xml
Sitemap: https://www.cdc.gov/std/STDsitemap1.xml
Sitemap: https://www.cdc.gov/grand-rounds/sitemap.xml

robots.txt versions

From	Through	State	Version
2026-10-26	2026-10-27	ok 200	`2837016c2084`

Timeline of changes

Date	What changed
No changes since the first observation (2026-10-26).

Reconstructed history (Common Crawl)

From Common Crawl's robots.txt captures: what CCBot was served, one crawl per quarter. A separate series from the daily observations above; a 403 here means Common Crawl was refused, not this ledger.

Crawl	Host	State	GPTBot	OAI-SearchBot	ChatGPT-User	ClaudeBot	Claude-SearchBot	Claude-User	PerplexityBot
2026-09-21 CC-MAIN-2026-39	cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2025-09-15 CC-MAIN-2025-38	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2024-09-16 CC-MAIN-2024-38	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2023-10-02 CC-MAIN-2023-40	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2022-10-03 CC-MAIN-2022-40	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2021-09-27 CC-MAIN-2021-39	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2020-09-28 CC-MAIN-2020-40	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2019-09-23 CC-MAIN-2019-39	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2018-09-24 CC-MAIN-2018-39	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2018-01-29 CC-MAIN-2018-05	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2017-10-23 CC-MAIN-2017-43	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2017-09-25 CC-MAIN-2017-39	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2017-07-24 CC-MAIN-2017-30	www.cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2017-04-24 CC-MAIN-2017-17	cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2017-01-23 CC-MAIN-2017-04	cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2016-10-03 CC-MAIN-2016-40	cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows
2016-09-05 CC-MAIN-2016-36	cdc.gov	ok view	allows	allows	unknown	allows	allows	unknown	allows

Evidence

Every daily observation of cdc.gov is a leaf in that day's Merkle tree. Proof of the robots.txt line for 2026-10-27: audit path (JSON), day root and OpenTimestamps proof (complete (bitcoin block 973493)).

API: https://infrarabbit.com/crawlers/api/v1/policy/cdc.gov