What's My IP / Browser Info

How What's My IP / Browser Info Works

Checking "what's my IP" usually means a page that quietly ships your IP address off to a third-party lookup service. This tool doesn't need to -- your IP is already sitting right there in the HTTP request your browser just sent to load this page, so it's read directly off that request, server-side, with nothing forwarded anywhere else.

Formula & Method

The server reads $_SERVER['REMOTE_ADDR'] -- the IP address the web server itself sees the connection coming from -- but checks the X-Forwarded-For header first, since production hosting commonly sits behind a reverse proxy or load balancer, which would otherwise make REMOTE_ADDR show the proxy's own address for every single visitor rather than each visitor's real one. Everything else on the page -- browser, OS, screen resolution, timezone, language, and so on -- comes from the browser's own JavaScript APIs (navigator, screen, Intl), parsed entirely client-side after the page loads.

Worked Example

A request arriving through a reverse proxy typically carries an X-Forwarded-For header like 203.0.113.42, 10.0.0.5 -- a comma-separated chain where the first address is the original client and later addresses are intermediate proxies. This tool takes only the first entry, since that's the actual visitor; the rest are the proxy hops themselves, not the visitor's IP.

Frequently Asked Questions

Why does this need to check X-Forwarded-For instead of just using REMOTE_ADDR directly?

On any server sitting behind a load balancer, CDN, or reverse proxy (extremely common in production hosting), REMOTE_ADDR reflects the IP of that proxy, not the actual visitor -- every visitor would appear to have the exact same IP address, which defeats the entire purpose of a "what's my IP" tool. The X-Forwarded-For header is how proxies pass along the real client IP, so checking it first gives the actual answer.

Is the browser and OS detection perfectly reliable?

No -- it's a best-effort parse of the User-Agent string your browser sends, and User-Agent strings are notoriously inconsistent: some browsers deliberately spoof or simplify theirs for compatibility reasons, and browser vendors have been gradually freezing or reducing the detail in User-Agent strings for privacy reasons. Treat the Browser/OS fields as a reasonable guess, not a guaranteed-accurate identification.

Does this tool send my information anywhere?

No -- your IP is read and displayed by this server alone (the same server your browser already contacted to load the page), and every other detail (screen size, timezone, language, etc.) is read and displayed entirely inside your own browser via JavaScript, without being transmitted to this server or anywhere else.

Why does my IP address here sometimes differ from what other "what's my IP" sites show?

If you're on a network using IPv6 and IPv4 simultaneously, different services may report different address families depending on which protocol that particular connection used. It can also differ if your connection is routed through a VPN, corporate proxy, or mobile carrier NAT between checks -- since this tool (and any other) can only ever report the address the server actually saw the request arrive from.