IP Blacklist Checker

Test an IPv4 address against eight major DNS blocklists at once. The checker reverses the IP, queries each DNSBL zone in parallel over secure DNS, and shows a per-list table of Listed, Clean or Unknown. Some lists refuse queries from large public resolvers, so an Unknown there is expected and means neither clean nor listed. Live and private in your browser.

Read the guide: How to Check If an IP Is Blacklisted
Enter an IPv4 address to test it against 8 major DNSBL blocklists at once.

How it works

  1. 1

    Enter the IPv4 address

    Type the address you want to test, such as a mail-server or office IP. DNSBLs are queried by IPv4.

  2. 2

    Run the check

    Press Check blacklists. The tool queries all eight blocklists at the same time over secure DNS.

  3. 3

    Read the table

    See each list with a Listed, Clean or Unknown verdict and the returned code, plus a count of how many lists flagged the IP.

Instant & 100% private — nothing is uploaded

Everything runs locally in your browser. Your code, text and files are processed on your own device and are never sent to a server — so there are no upload waits, no size limits from us, and nothing is ever stored or logged.

Frequently asked questions

What is a DNSBL?
A DNSBL (DNS-based blocklist) is a list of IP addresses with a poor sending reputation, published over DNS. To check an address, its octets are reversed and prepended to the list zone, then resolved; an answer in the 127.0.0.0/8 range means listed, and no record means not listed. Mail servers query these lists to decide whether to accept a connection.
Why do some lists show Unknown instead of a verdict?
Several blocklists, Spamhaus most notably, refuse queries that arrive through large public DNS resolvers. Because this tool queries over a public resolver, those lists may return an error or a non-standard code rather than a clean or listed answer. An Unknown there means the list could not be reached from here — it is not a pass and not a listing. For a definitive answer on those, query the list from your own mail server resolver.
I am listed — what do I do?
Open the listing on the blocklist that flagged you to see the reason, fix the underlying issue (compromised account, open relay, spammy mail, or just a new IP with no history), then use that list delisting process. Delisting is per-list, and some lists clear automatically once the bad behaviour stops.
Does the check store my IP?
No. The queries run in your browser against a public DNS resolver over a secure connection. We do not log the address you enter or the results.

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