# ip-tools.eu

> A live read-out of the connection that opens it: public IPv4 and IPv6 address, location and ASN, TLS and TCP fingerprints, passive OS detection, DNS resolver behaviour, NAT and path probes, and a weighed verdict on VPNs, proxies and carrier-grade NAT. A program gets the same about its own connection from the API.

Every page is available as markdown at its `.md` path or with `Accept: text/markdown`. The API is documented in [docs/api.md](https://ip-tools.eu/docs/api.md) and described by [openapi.json](https://ip-tools.eu/openapi.json).

## Your connection

- [What Is My IP Address? IPv4, IPv6, Location & Fingerprint](https://ip-tools.eu/index.md): Your public IPv4 and IPv6 address, location, ISP and ASN, plus what the connection reveals: TLS and TCP fingerprints, OS and DNS resolver.
- [IP geolocation and IPv6 test: where your address is placed and who announces it](https://ip-tools.eu/network.md): Where your IP address is placed, which network announces it, whether IPv6 works and how your IPv6 address was assigned, next to IPv4.
- [DNS resolver check: which resolver your device really uses](https://ip-tools.eu/dns.md): Which DNS resolver your device really uses, whether it validates DNSSEC, randomises source ports, minimises queries and forwards your subnet.
- [TLS fingerprint check: your browser's JA4, JA3 and HTTP/2 fingerprint](https://ip-tools.eu/fingerprint.md): Your browser's TLS fingerprint (JA4, JA3), HTTP/2 fingerprint and header order, and whether they match what the User-Agent claims.
- [TCP fingerprint and passive OS detection from your own packets](https://ip-tools.eu/connection.md): Your TCP SYN fingerprint (JA4T), passive OS detection with p0f, live kernel TCP_INFO, the handshake timeline and the captured packets.
- [NAT type, path MTU, HTTP/3 and the route back to you](https://ip-tools.eu/path.md): NAT mapping via STUN, HTTP/3 over QUIC, the largest packet your path carries, IPv6 extension headers and a reverse traceroute to you.
- [Browser fingerprint and TLS policy test](https://ip-tools.eu/browser.md): What your browser reports about itself and its device, which TLS versions and key exchanges it refuses, and what WebRTC exposes.
- [Latency, jitter and bufferbloat test](https://ip-tools.eu/tests.md): Measure latency, jitter and bufferbloat under load, with live kernel TCP statistics streamed from your own socket.

## Tools

- [IP address lookup](https://ip-tools.eu/geoip.md): Look up any IPv4 or IPv6 address: country, city, coordinates, time zone, ISP and ASN, from an offline GeoIP database.
- [IP subnet calculator](https://ip-tools.eu/calc.md): Subnet calculator for IPv4 and IPv6: CIDR to range, split into subnets, aggregate ranges and convert notations. Runs in your browser.

## Reference

- [Networking glossary](https://ip-tools.eu/glossary.md): Plain-English definitions of the terms behind IP addresses, TLS and TCP fingerprints, DNS resolvers, NAT and network paths.
- [API documentation](https://ip-tools.eu/docs/api.md): endpoints, hosts, fields and limits, with curl examples.
- [OpenAPI description](https://ip-tools.eu/openapi.json): machine-readable description of the API.
- [Agent skill](https://ip-tools.eu/skills/ip-tools/SKILL.md): how a program checks its own connection with this site.