IP blacklist checker
An IP blacklist check tells you whether an address is listed on public spam and abuse blocklists (DNSBLs) that websites and mail servers use to block traffic. This free checker queries 10 public lists at once, starting with your own IPv4 address.
How the blacklist checker works
- 1
Reverse the address
203.0.113.10 becomes 10.113.0.203, the format DNS blocklists use for lookups. - 2
Query every list in parallel
Our server asks each blocklist's DNS zone whether that name exists. An answer in 127.0.0.x means listed; no record means not listed. - 3
Read the reason
When an IP is listed, we fetch the list's TXT record, which often links to details and a delisting page. - 4
Show a clear verdict
Each list shows Listed, Not listed or Timed out. Results are cached for 10 minutes and nothing is logged.
Why IP reputation matters for proxy users
A proxy is only as good as the reputation of its IP. Listed addresses trigger CAPTCHAs, login challenges and outright blocks long before your request reaches the page, and on shared proxy pools you inherit whatever the previous users did.
Fewer CAPTCHAs and blocks
Account safety
Email deliverability
Check before you rely on an IP
If your IP is listed
- Open the list's page from the results to read why the IP was listed and when.
- Scan the devices behind the IP for malware, and check mail servers for open relays or hacked accounts.
- Request removal through the list's own form once the cause is fixed; many lists also expire entries on their own.
- On a proxy, ask your provider for a replacement IP. With dedicated IPs, a listing is rare and easy to trace.
Want to know who owns a listed address? Run it through the IP lookup for its network, ASN and abuse contact.
Frequently asked questions
An IP blacklist, or DNS blocklist (DNSBL), is a public list of addresses seen sending spam, running attacks or showing other abuse. Mail servers, firewalls and anti-bot systems query these lists in real time and block or challenge traffic from listed IPs.