Measures latency (ping + jitter), download (6 parallel streams), and upload (4 parallel chunked POSTs) against this edge. Your requests are served from the Cloudflare location nearest you.
Downloads stream random bytes (up to 100 MiB per request) and uploads are capped at 16 MiB per request; both phases run for ~10 seconds. Per-IP rate limiting protects the endpoints (200 requests/minute). Browser measurement includes TLS and HTTP overhead, so expect slightly lower numbers than a native client.