IP Checker: What Is My IP Address and Do Sites See a Proxy?

Each check sets two things a website can see side by side. A fail does not prove a proxy, but it is the kind of sign anti-fraud systems collect.

Checks 9 and 10 read the connection, not the browser. Each operating system builds TCP packets its own way: Windows starts them with a time to live (TTL) of 128, while Linux, Android, macOS and iOS start with 64, and each has its own window size and order of options. Matching these against known systems, as the p0f tool does, names the system. Through a proxy, the TCP connection that reaches the checker is the proxy side's, so a Windows browser can arrive on a connection that looks like Linux, and check 9 fails. A VPN works the other way. Your own device builds the packets, so check 9 passes, but every packet also carries the tunnel's headers, so the MTU drops below the usual 1,500 bytes (1,420 is WireGuard's usual default). PPPoE, used on some DSL and fiber lines, runs at 1,492, which is why a lowered MTU is a hint, not proof.

Check 4 only sees headers a proxy can add. In an HTTPS connection, an ordinary proxy tunnels encrypted bytes and cannot add a header. Proxy headers show up when a proxy handles plain HTTP, or when it decrypts HTTPS, as some company filters and antivirus programs do.

Check 6 never fails on its own. An English browser on a German IP is normal for many people, so the check shows a warning at most. Sites treat language as one signal among several.

Checks 7 and 8 are quick versions. Check 7 flags a public WebRTC address that differs from this IP; the WebRTC leak test lists every address, local ones too. Check 8 makes 2 lookups; the DNS leak test makes 6 and shows each resolver.

Few sites rely on one signal. Anti-fraud and bot-management systems combine several, and the 10 checks cover the ones that come from the IP and the connection:

• The IP's network. IP data vendors label address ranges by who runs them: hosting and cloud companies, VPN providers, Tor exits, home ISPs and mobile carriers. A datacenter or VPN label is a common reason for a CAPTCHA page or a block. What those labels mean, and the messages they cause: anonymous proxy detected.
• Reputation. An IP that sent too many requests, or that sits on a blocklist, can be flagged whatever its type. This checker does not score reputation; see blacklisted IP address.
• Consistency. A time zone, language or DNS resolver from another country than the IP, or a TCP connection from another operating system than the browser's, suggests the traffic is relayed.
• Leaks. WebRTC and DNS can show your own IP or provider next to the proxy's.
• The browser. Fingerprint values that contradict each other, automation traces and a TLS handshake that does not fit the browser; the browser leaks test covers these.

What a site does with the signals is up to the site: one shows a CAPTCHA, another asks for a login code, a third blocks the request. Detection by proxy type, in more depth: can websites detect proxies.

The IP type comes from ProxyField's own rules on the IP's network: its ASN, the name registered for that network and the IP's reverse DNS hostname. The checker says which rule applied, so you can judge it yourself.

• Reverse DNS is a hint. Home lines often have hostnames that name the provider's access network or an address pool; servers usually have a name their owner chose, or none.
• An ISP proxy can show as datacenter. ISP IPs are registered to consumer ISPs and run on server connections. A checker that reads the registered network calls them Residential; one that also weighs the hosting, the hostname or the block's history can call them Datacenter.
• Mobile IPs are shared and move. Carriers send many phones through a few gateways and share each public address among many subscribers, so a mobile IP often shows the carrier's gateway city, not yours.
• A VPN can look residential. Some VPN services use addresses in home ISP networks. The VPN flag appears only when the network belongs to a known VPN provider, so check 2 can pass while checks 5 or 10 do not.

An IP address carries no location. Databases map address blocks to places from registry records, provider data and measurements, and this checker uses the DB-IP Lite databases (DB-IP, CC BY 4.0), refreshed monthly. The country is usually right; the city often is not, and the coordinates are the middle of the area the database names, not your street. The usual reasons for a wrong city:

• Central registration. A provider can register a block at its head office and use it across the country.
• Gateways. Mobile carriers and some fiber networks bring traffic out in a few cities, so the IP sits where the traffic exits.
• Moved blocks. An address block that changed owner or region keeps its old location until the databases catch up.
• A relay in between. Behind a VPN or a proxy, the location is the server's, which is the point.

Your browser's own location is a different thing: a site that asks for location permission gets GPS or Wi-Fi positioning, not the IP's place. Because each checker uses its own database and update date, two checkers can show two cities for the same IP. Trust the country.

After each change, press Run again: a fixed setting shows up at once.

A proxy and a VPN both replace your IP, but they leave different traces in the 10 checks.

So a VPN tends to show in checks 2 and 10 and a proxy in checks 7 and 9, and neither changes checks 5 and 6, which are browser settings. More on the two: proxy vs VPN.

• Different databases. Each checker looks your IP up in its own location and network data, updated on its own schedule.
• Different labels. One checker flags only known VPNs and proxies, another every hosting network, a third uses a fraud score.
• IPv4 and IPv6. A checker you reach over IPv6 sees your IPv6 address, which can belong to another network or skip a VPN that tunnels only IPv4. This checker shows both addresses when your browser reaches it over both.
• Rotation. A rotating proxy gives new requests a new exit IP, so two checkers, or two runs, can test two IPs.
• What is read. Some pages show the IP your browser reports through WebRTC rather than the connection's, which is the wrong one behind a proxy.

To compare proxies rather than your own connection, the proxy checker tests up to 100 at once.

Everything on this page is visible to any site you open, without a permission prompt: your IP and its network, the headers your browser sends, your time zone and languages, the addresses WebRTC gives page scripts, the resolver your lookups come from and the traits of your TCP connection. The checker shows them so you see what a site works with.

An IP address does not give a site your name or street address: your internet provider knows which customer used it, while the site sees only the address and the rough place a database gives it.