My IP and connection

Everything is checked as soon as the page opens; Refresh runs it again and Copy all as JSON copies the lot.

What it checks, and how

Public IPv4, IPv6, and preferred family — three requests to ipify: api.ipify.org (IPv4 only), api6.ipify.org (IPv6 only: if it fails, your connection has no working IPv6), and api64.ipify.org (dual stack: shows which family your browser chose).
Cloudflare edge — www.cloudflare.com/cdn-cgi/trace reports the data centre that served you (an airport code such as SJC), your country, and the HTTP version, TLS version, and key exchange your browser negotiated.
Network owner and location — only when you press the button (or tick Always look up): the third-party service ipwho.is, falling back to geojs.io, maps your IP address to an organisation, ASN, and approximate place. IP location is often only your provider’s nearest hub.
WebRTC candidates — opens a WebRTC connection to Google’s public STUN server (stun.l.google.com) and lists the candidates a peer would see. Your local address appears as a random .local (mDNS) name: browsers hide it on purpose.
Connection — the Network Information API’s estimates (effective type, downlink, round trip, data saver), where the browser supports it (Chromium-based browsers do; Safari and Firefox do not).
Browser and device — user agent and client hints, languages, time zone, screen, colour scheme, CPU threads, memory class, and privacy signals.

Browsers cannot see your Wi-Fi network, MAC address, gateway, or traceroute, and cannot send ICMP pings; tools that need those must run outside the browser.