The 'What's My IP' Sites
How 'What's My IP' Tools Actually Work
It can feel like magic: you open a page and it instantly knows your IP address, your city, and your ISP. There's no magic — just a clever use of how the web works.
The server sees your address automatically
The core trick is simple: to send you any web page at all, the server must receive your request — and every request carries your public IP address as its return address. The server doesn't have to detect anything; the address is simply there, the same way a letter's envelope carries a return address. A "what's my IP" tool just reads that value and shows it to you.
Why your own computer can't tell you directly
You might ask why you need a website at all. It's because your device only knows its private address behind the router (like 192.168.x.x). Your public address is assigned to the router and applied by NAT as traffic leaves your network. The only way to see the public address your device uses is to ask something on the outside — which is exactly what these tools are for.
Adding location and ISP
Once a tool has your IP, it can look up more:
- Geolocation: the address is checked against a database that maps blocks to approximate places.
- ISP and ASN: registry data reveals which network owns your address block.
- Reverse DNS: a PTR lookup can turn your IP back into a hostname.
The modern twist: doing it in your browser
Older tools did all of this on their own servers. Modern tools like IP Ducky can do it client-side — the JavaScript in your browser calls public APIs directly to fetch your IP, geolocation, and hostname, then reads device details from the browser itself. Nothing needs to be stored on the tool's own servers, which is better for both speed and privacy.
The device details
Facts like your browser, operating system, screen size, and time zone don't come from your IP at all — the browser exposes them through standard web APIs. That's why a good "what's my IP" tool can show a rich picture of your connection and device without any special access: it's simply reading information the web already makes available.