How each measurement is taken
Every number on this site comes from somewhere, and each source has an edge past which it stops being true. Both are written down here.
Address and location
| IP address | Read from the connection at the edge. It cannot be spoofed by a request header, because the header is overwritten before our code sees it. |
| Country, city | Resolved at the edge from the connecting address. City-level geolocation is an estimate everywhere in the industry; treat it as a region, not an address. |
| Timezone | Derived from the address, not from your machine. When it disagrees with the timezone your browser reports, that difference is itself a signal. |
Network
| AS and ISP | Looked up in the DB-IP ASN database, which ships inside this deployment and is refreshed monthly. No third party sees your address for this. |
| Usage type | An inference, not a lookup. It combines the PeeringDB classification of the autonomous system with patterns in the operator name. It separates a phone from a data centre reliably; it is not authoritative. |
Leaks
| WebRTC | The browser is asked to gather ICE candidates through a public STUN server. Any address that appears here is one a website can read without your involvement. Local addresses are usually absent by design: browsers have replaced them with mDNS names since Chrome 74. |
| IPv6 | Requested from an IPv6-only host, because our own edge accepts IPv4 only. If an address appears here while your IPv4 goes through a tunnel, IPv6 is bypassing it. |
Fingerprints
| JA4 | Computed by the edge from the TLS ClientHello and passed to us as a header. |
| What is not here yet, and why | JA3, JA4T and the HTTP/2 Akamai hash are measured from the raw SYN packet and the unparsed TLS and HTTP/2 frames. This deployment terminates TLS at a managed edge, which consumes all of that before our code runs. Measuring them needs a host that owns its own socket, which is being built; until it is, those rows are marked as pending rather than filled with a plausible number. |
What we keep
| Measurements | Nothing. Reports are generated per request and not written down. |
| Baselines | The compare feature stores your saved baseline in your own browser. It is never transmitted to layerleaks.io, which is why comparing works offline from our side and why clearing your browser data deletes it for good. |