Reverse IP Lookup
Enter an IP address to see which domains point at it, or a hostname to find the server it runs on and everything else hosted there.
How to use reverse IP results
During reconnaissance a reverse IP lookup turns one known address into a list of neighbours. If a target's mail server or staging host shares an IP with other names, those names are often owned by the same team and worth checking with the subdomain finder.
For defenders it answers a simpler question: what else lives on the same box as your site? A compromised neighbour on shared hosting is a real risk, and so is an old hostname you forgot still points at a live server.
Frequently asked questions
What does a reverse IP lookup show?
It lists the domain names that have been seen resolving to an IP address. On shared hosting that can be hundreds of unrelated sites. On a dedicated server it is usually one organisation's own hostnames, which makes it a quick way to find related infrastructure.
Where does the data come from?
Two passive sources queried in parallel: the ip.thc.org domain database and the C99 reverse IP index. Results are merged and each row shows which source reported it. No traffic is sent to the IP you look up.
Why are some domains missing?
Passive databases only know names they have observed in DNS or certificate logs. A new site, or one behind a CDN such as Cloudflare, may not be listed, and CDN addresses are shared by so many sites that the list is only a sample.
Can I look up a hostname instead of an IP?
Yes. The hostname is resolved first, the lookup runs on its first public IPv4 address, and any other addresses it resolves to are offered as one-click follow-up lookups.
Free to use within a daily limit per visitor. Use it on systems you own or are allowed to test, see the acceptable use policy.