Reverse IP lookup: find the contact behind an IP address

Give an IP address and get back the contact and household details linked to it, when a record exists. Use it to put a name to anonymous website traffic, or to fill in contact detail on an inbound lead.

What it tells you

• Whether a record was matched at all, so you can tell a real hit from an empty result.
• The first and last name linked to the address.
• An email address for that contact.
• Location detail behind the address: city, region, country code and ZIP code.
• The credits the lookup used and your remaining balance.

What you need to provide

One input: the IP address you want to resolve. Both IPv4 (the familiar four-number format) and IPv6 (the longer, newer format) are accepted.

What it costs

10 credits per lookup. Live per-product costs are shown on the Billing page in your dashboard.

How to run it

• In the dashboard: Reverse IP Lookup
• From your code: POST /v1/reverse-ip-append, then see the Developer Hub at app.1lookup.io/developer-hub.

Good to know

• Not every IP address has a record behind it. Check the matched flag first, because an unmatched lookup still returns a response, just without contact detail.
• This returns personal data about identifiable people. Use it for legitimate business purposes only.
• Results are point-in-time. IP addresses are shared and reassigned, so the contact behind one can change after your lookup, and a match reflects what the data showed at the moment you ran it.
• One IP address can cover a whole household or office. Treat a match as the people associated with that connection, not proof of who was at the keyboard.
• This costs more per lookup than a standard IP lookup, so run it on the addresses you actually want contact data for rather than on all traffic.

Updated on: 24/08/2026