What is my public IP address and what does it reveal?

A public IP address is the address a website or lookup service sees for the connection that reached it. On this site, What is my IP asks free providers from this browser, so the number is yours for that request — not the address of this site’s hosting server.

It is not a street address. It is not a name. It is not proof that you are logged into an account. Empty city or ISP fields mean the provider did not return them. They are not guessed.

What the lookup actually returns

Typical fields, when present:

• The IP string (IPv4 or IPv6)
• Country, sometimes city
• Timezone
• ISP and ASN

Country and city are geolocation database guesses, not GPS. Two websites can disagree. A VPN exit can look like a neighbouring country or a datacenter suburb. Why a VPN location can look wrong covers that mismatch.

ASN and ISP can be more informative than a city name. A hosting ASN with your old residential ISP still listed is a stronger “this path did not move” clue than a flag.

Observation vs inference vs certainty

Observation: “The lookup provider returned this IPv4 address and this ISP string.”

Inference: “This browser’s HTTPS request to that provider used that path.”

Not proven: “We know your home,” “we detected a VPN,” or “you are anonymous if this number changes.”

No website can reliably prove that a VPN is enabled from a single lookup. Matching or changing IP, country, and ISP are clues about the path this browser used.

What websites can learn from an IP

A site you visit sees an address for that HTTPS connection. From it, operators may:

• Apply coarse geolocation (often country-level, sometimes city-level and wrong)
• Apply rate limits or blocklists
• Compare the address with hosting or VPN ranges — those lists can be wrong
• Combine the address with cookies and an account, which is much stronger than IP alone

They do not magically receive your legal name from the IP string. They might receive it from an account you opened.

Browser fingerprinting explained is the other half: language, timezone, and screen stay visible even when the IP changes.

What a public IP does not reveal

A lookup cannot tell a website your passport number, your street, or whether you are the only person on a CGNAT connection. Carrier-grade NAT means many customers can share one public IPv4 address. The reverse is also true: one household can present several public addresses over a day if the ISP rotates them, a phone leaves Wi‑Fi, or a VPN connects.

“Why did my IP change?” is therefore often boring: DHCP lease, mobile network, reconnect, or a tunnel. It is not automatically evidence of compromise. Compare two lookups from the same browser if you need a real before/after.

Shared office, campus, and coffee-shop networks also present one public IP for many people. Seeing “your” public IP on a leak page does not uniquely name you on that LAN.

IPv4 and IPv6

You may have both. The main lookup might show one family while the IPv6 test shows another. Dual-stack routes can differ. A visible IPv6 address means this browser currently has IPv6 connectivity. That is not, by itself, a VPN leak. Read IPv6 exposure vs a VPN leak.

Incognito does not hide the IP

A private window still makes HTTPS requests from a public address. Does incognito mode hide your IP address? answers that directly.

If you use a VPN

Check substitution with a before/after, not a vibe. Does a VPN hide your IP address? explains what “hide” can mean. How to test privacy before and after a VPN is the method. Use the VPN test so you are not relying on memory.

If the app says connected and the string does not move, this browser is not on the exit yet. That is a routing problem, documented in VPN connected but the IP is not changing.

What this lookup cannot do

• DNS leak testing (not in this project)
• See other apps on the device
• Prove anonymity
• Fill in missing city data

Do not paste the complete public IP into a public comment if you can avoid it. Share redacted prefixes if you need help.

Practical takeaway

Use the local lookup to answer “what address did this browser just present?” Treat geo fields as optional, fallible context. If you need to know whether a VPN changed that address, compare before and after on the same browser. Stop at what the numbers show.