Anthropic crawler IPs can be silently blocked by AbuseIPDB reputation filters

Ill-Pack-9105 · reddit · 2026-07-23

A site operator says one of Anthropic’s published crawler IPs was silently blocked because it was flagged 100% on AbuseIPDB, even though robots.txt was open and other AI crawlers could fetch the same docs.

The post explains that many CDN/WAF reputation blocklists are default-on, so a crawler can be denied before robots logic runs. In this case, Anthropic’s shared cloud IPs appear to have accumulated abuse reports, which can cause legitimate crawls to fail without obvious monitoring signals.

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