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Longest Match

Look up any IP address: location, network, operator, registered holder, and VPN or proxy signals. Use it in the browser, or call the API.

Open longestmatch.com ↗ All products
longestmatch.com/169.150.197.40 Open ↗ Longest Match showing its lookup result for 169.150.197.40: location, network and assessment.

Fig. 01 · longestmatch.com/169.150.197.40, captured September 2026

02 / Spec sheet

At a glance

Status
Live
Domain
longestmatch.com
For
Developers, fraud and trust teams, network engineers
Platform
Web and REST API
API
v2.3.0, versioned with a public changelog
Stack
Python, FastAPI, PostgreSQL, React
Data
Public registry, routing, geolocation and reputation datasets
Free tier
1,000 lookups a day with a free account
Started
August 2026
Addresses
IPv4 and IPv6
03 / Features

What it does

Address lookup

Location, network, operator and registered holder for any IPv4 or IPv6 address.

Anonymizer signals

VPN, proxy, Tor and hosting signals, each graded by how strong the evidence behind it is.

Network directory

Browsable pages for networks, operators, organisations, VPN providers and countries.

Batch lookups

Up to 100 addresses in a single API request.

Routing context

The announcing network, the enclosing block and what surrounds an address.

Two-source geolocation

A city is published only when two independent sources agree on it.

04 / Build

How it is built

The principles behind Longest Match, and the choices that follow from them.

01

Own the data

Every answer comes from data we collect and hold ourselves. A lookup never waits on another company's service, and keeps working when one of them has a bad day.

02

Do the heavy lifting ahead of time

When new data arrives, the expensive work runs once in the background. Visitors get pages that were prepared in advance, so they open in milliseconds.

03

Cross-check before publishing

A city is shown only when independent sources agree on it. When they disagree, the city is left out and the country stays.

04

Say how sure we are

Every signal carries a grade for the evidence behind it, so a strong finding and a weak hint never look the same.

05 / Recent work

What got better lately

4 improvements

  • Longest MatchCheck up to 100 addresses in a single request with batch lookups
  • Longest MatchSign up and get an API key straight away
  • Longest MatchMore reliable city locations: a city is shown only when two independent sources agree
  • Longest MatchLongest Match launches, with address lookups and a browsable network directory