IP geolocation with zero external APIs, the Cloudflare Workers cf object
When I built whatsmy.fyi , I assumed I'd need a geolocation provider: MaxMind, ipinfo, ip-api, pick your poison. They all mean the same thing: an external dependency, an API key, a quota, added latency, and someone else's server seeing your users' IPs. Then I found out Cloudflare Workers makes the whole category unnecessary. The cf object Every request that hits a Cloudflare Worker carries a request.cf object, populated at the edge before your code even runs. No lookup, no latency, no key. Here's what's inside: { asn : 34984 , // ISP's autonomous system number asOrganization : " Superonline " , // ISP name city : " Istanbul " , region : " Istanbul " , country : " TR " , continent : " AS " , isEUCountry : undefined , // "1" if EU, undefined otherwise latitude : " 41.01380 " , // string, not number! longitude : " 28.94970 " , postalCode : " 34000 " , timezone : " Europe/Istanbul " , colo : " IST " , // which CF datacenter handled this clientTcpRtt : 12 , // user's RTT to the edge, in ms httpProtocol : " HTTP/3 " , tlsVersion : " TLSv1.3 " , tlsCipher : " AEAD-AES128-GCM-SHA256 " } That last group surprised me most: you get the user's HTTP protocol, TLS version, and actual TCP round-trip time for free. Try getting that from a geo API. A complete IP endpoint in ~30 lines export default { async fetch ( request ) { const cf = request . cf ?? {}; const ip = request . headers . get ( " CF-Connecting-IP " ); return Response . json ({ ip , city : cf . city ?? null , country : cf . country ?? null , isp : cf . asOrganization ?? null , asn : cf . asn ?? null , timezone : cf . timezone ?? null , lat : cf . latitude ? parseFloat ( cf . latitude ) : null , lng : cf . longitude ? parseFloat ( cf . longitude ) : null , protocol : cf . httpProtocol ?? null , tls : cf . tlsVersion ?? null , rttMs : cf . clientTcpRtt ?? null , }); }, }; That's the entire backend. No database, no GeoIP file to update monthly, no vendor. The gotchas (learned the hard way) 1. Coordinates are strings. lati