At its homepage, nih.gov is protected by Cloudflare. Typical approach to reach it reliably: Browser-impersonation HTTP (matched TLS). Difficulty is per-URL, so deep pages — profiles, listings, search — are usually harder.
Wants a browser-impersonation HTTP client with a matched TLS fingerprint and realistic headers.
Typical access
TLS match
Detected vendors
Evidence
Detection confidence: high · vendor present but served clean (passive edge, not an active challenge)
Homepage-level, datacenter-IP snapshot, June 13, 2026.
This is a homepage-level snapshot and can be inaccurate or out of date — anti-bot vendors update their models continuously, deep pages are usually more protected than the homepage, and difficulty is IP-sensitive: a site can read differently from a clean vs a flagged IP and even flip over time. Treat it as a directional signal, not a guarantee.
The homepage is the open front door. On a government site the valuable pages behave differently — here's the plan to characterise nih.gov before you build.
Article / entry
usually openReference content is usually open.
Search
rate-limitedOpen but rate-limited at volume.
Find a real deep URL cheaply from the site’s robots.txt and sitemap.xml, then run each through the anti-bot checker. This is an advisory based on the category and nih.gov’s homepage result — detect the wall, never try to pass a login.