IAS crawler user agent
Operated by Integral Ad Science
IAS crawler is the brand safety and verification crawler of Integral Ad Science.
The IAS crawler bot at a glance
- IAS crawler is operated by Integral Ad Science and checks landing pages for an advertising platform.
- The robots.txt token for IAS crawler is ias_crawler.
- Blocking a platform fetcher has no effect on organic search rankings.
- IAS crawler robots.txt support: Not documented.
- Recommendation for Generative Engine Optimization (GEO): Allow.
What is IAS crawler?
IAS crawler classifies pages so advertisers can avoid unsafe placements.
Ad-supported publishers should allow it to stay eligible for brand-safe campaigns.
Should you block IAS crawler?
Allow IAS crawler unless it causes a measurable load problem.
| Effect on search rankings | Blocking a platform fetcher has no effect on organic search rankings. |
|---|---|
| Effect on AI visibility | Blocking breaks the feature the fetcher serves, such as ad approval or feed updates. |
| Follows robots.txt | Not documented |
| Recommendation | Allow |
How to block or allow IAS crawler
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 ias_crawler is matched case-insensitively. robots.txt alone may not stop IAS crawler, so add the Nginx, Apache or Cloudflare rule as well.
robots.txt: block
# Block IAS crawler
User-agent: ias_crawler
Disallow: /robots.txt: allow
# Allow IAS crawler
User-agent: ias_crawler
Allow: /robots.txt: partial
# Keep IAS crawler out of private areas only
User-agent: ias_crawler
Disallow: /wp-admin/
Disallow: /cart/
Disallow: /checkout/
Disallow: /my-account/
Allow: /Nginx
# Nginx: return 403 to IAS crawler
if ($http_user_agent ~* "(ias_crawler)") {
return 403;
}Apache
# Apache .htaccess: return 403 to IAS crawler
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} (ias_crawler) [NC]
RewriteRule .* - [F,L]Cloudflare WAF
# Cloudflare > Security > WAF > Custom rule, action: Block
(http.user_agent contains "ias_crawler")How to verify real IAS crawler traffic
Integral Ad Science publishes no IP list or reverse DNS pattern for IAS crawler, 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 IAS crawler in your server logs
Search the web server access log for the token. The command below counts IAS crawler requests per URL on Nginx or Apache.
grep -i "ias_crawler" 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.
IAS crawler user agent string
The full user agent Integral Ad Science publishes for IAS crawler. Version numbers such as Chrome/W.X.Y.Z change over time, so match the token, not the whole string.
IAS crawler (ias_crawler; http://integralads.com/site-indexing-policy/)IAS crawler FAQ
IAS crawler identifies itself with the robots.txt token "ias_crawler". A typical request header reads: IAS crawler (ias_crawler; http://integralads.com/site-indexing-policy/)
Integral Ad Science has not documented how IAS crawler treats robots.txt. Add a robots.txt rule and back it with a server rule if the traffic matters to you.
Blocking a platform fetcher has no effect on organic search rankings. Blocking breaks the feature the fetcher serves, such as ad approval or feed updates.
Add two lines to the robots.txt file at the root of each domain and subdomain: "User-agent: ias_crawler" followed by "Disallow: /". The token is case-insensitive. Changes can take up to 24 hours to be picked up.
Not reliably. Integral Ad Science publishes no IP list or reverse DNS pattern for IAS crawler, so anyone can send the same user agent. Rate-limit unusual volume instead of trusting the name.
Search your server access log for "ias_crawler", for example with: grep -i "ias_crawler" 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.
