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DNS & Infrastructure
Blacklist Checker
Check any IP or domain against 40+ blacklists including Spamhaus, Barracuda, SORBS, SpamCop, and UCEPROTECT.
About this check
Check IPs and domains against 40+ RBLs in one click.
Frequently asked questions
- What does the Blacklist Checker actually check?
- Check IPs and domains against 40+ RBLs in one click.
- Is this really free?
- Yes. Every on.bo tool is free, no signup required, no rate-limit tricks.
- Do you store the data I check?
- We log minimal metadata to keep the service healthy. Lookups themselves are not retained beyond short-term caching.