Anatomy
When Cloudflare's WAF decides your client looks like a bot, the API stops returning JSON entirely and returns a 403 HTML challenge page. Clients that blindly call .json() on any 2xx/4xx response crash on the HTML — a real production failure mode for scrapers and SDKs.
Replay it
curl -i https://faultydata.com/r/FD-2026-008// response appears hereSignature
{Status:403 Headers:map[CF-Mitigated:challenge Content-Type:text/html; charset=UTF-8] Body:<!DOCTYPE html><html><head><title>Just a moment...</title></head><body><h1>Checking your browser</h1><p>Enable JavaScript and cookies to continue</p></body></html> Corrupt: Delay:<nil> Flaky:<nil> Sequence:<nil> Drip:<nil> StallAfter:0 Hang:false Phases:[]}