Diffbot-User user agent
Operated by Diffbot
Diffbot-User is the user agent Diffbot uses for requests made on behalf of a person browsing a URL with Diffbot software.
The Diffbot-User bot at a glance
- Diffbot-User is operated by Diffbot and fetches a page when a person asks an AI assistant about it or shares its link.
- The robots.txt token for Diffbot-User is Diffbot-User.
- Blocking an AI assistant fetcher has no effect on search rankings.
- Diffbot-User robots.txt support: Yes.
- Recommendation for Generative Engine Optimization (GEO): Allow.
What is Diffbot-User?
Diffbot-User fetches a page only in response to a user’s request.
Public registries report that it follows robots.txt.
Should you block Diffbot-User?
Allow Diffbot-User unless it causes a measurable load problem.
| Effect on search rankings | Blocking an AI assistant fetcher has no effect on search rankings. |
|---|---|
| Effect on AI visibility | Blocking stops the assistant from reading your page when a user asks about it or pastes your link, so its answer falls back to other sources. |
| Follows robots.txt | Yes |
| Recommendation | Allow |
How to block or allow Diffbot-User
Put the robots.txt rule in the file at the root of every domain and subdomain, for example https://example.com/robots.txt. The token Diffbot-User is matched case-insensitively.
robots.txt: block
# Block Diffbot-User
User-agent: Diffbot-User
Disallow: /robots.txt: allow
# Allow Diffbot-User
User-agent: Diffbot-User
Allow: /robots.txt: partial
# Keep Diffbot-User out of private areas only
User-agent: Diffbot-User
Disallow: /wp-admin/
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Allow: /Nginx
# Nginx: return 403 to Diffbot-User
if ($http_user_agent ~* "(Diffbot\-User)") {
return 403;
}Apache
# Apache .htaccess: return 403 to Diffbot-User
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} (Diffbot\-User) [NC]
RewriteRule .* - [F,L]Cloudflare WAF
# Cloudflare > Security > WAF > Custom rule, action: Block
(http.user_agent contains "Diffbot-User")How to verify real Diffbot-User traffic
Diffbot publishes no IP list or reverse DNS pattern for Diffbot-User, so the user agent cannot be verified. Anyone can send the same string. Rate-limit unusual volume instead of trusting the name.
How to find Diffbot-User in your server logs
Search the web server access log for the token. The command below counts Diffbot-User requests per URL on Nginx or Apache.
grep -i "Diffbot-User" access.log | awk '{print $7}' | sort | uniq -c | sort -rn | head -20For a full report per AI bot, upload the log to the AI Log File Analyzer, a free tool by Justin Hà.
Diffbot-User FAQ
Diffbot-User uses the robots.txt token "Diffbot-User". Diffbot does not publish a full user-agent string, so match the token inside the User-Agent header.
Yes. Diffbot states that Diffbot-User follows robots.txt rules written for the "Diffbot-User" token.
Blocking an AI assistant fetcher has no effect on search rankings. Blocking stops the assistant from reading your page when a user asks about it or pastes your link, so its answer falls back to other sources.
Add two lines to the robots.txt file at the root of each domain and subdomain: "User-agent: Diffbot-User" followed by "Disallow: /". The token is case-insensitive. Changes can take up to 24 hours to be picked up.
Not reliably. Diffbot publishes no IP list or reverse DNS pattern for Diffbot-User, so anyone can send the same user agent. Rate-limit unusual volume instead of trusting the name.
Search your server access log for "Diffbot-User", for example with: grep -i "Diffbot-User" access.log. The AI Log File Analyzer by Justin Hà counts visits per AI bot from an uploaded log file.
Sources: Public bot registry. Last reviewed by Justin Hà.
See which of these bots actually reach your website
The AI Log File Analyzer by Justin Hà counts visits from GPTBot, ClaudeBot, PerplexityBot and other AI crawlers in your server log, for free. The GEO Technical Package sets up robots.txt, llms.txt and crawler access for AI search.
