Cloudflare Speed Test
Measure your connection against Cloudflare’s network from the browser or the command line. Useful for checking what your link really delivers before blaming a Cloudflare Tunnel or a reverse proxy. Account-level Cloudflare topics are in Cloudflare.
Documentation: @cloudflare/speedtest · worker-speedtest-template
Verification: the
curlcommands below were run once and worked. The__downand__upendpoints are community-documented only: Cloudflare publishes no official curl guide for them, and they may change. For a single transfer they measure one connection, so use iperf3 for a LAN or server-to-server test.
Browser #
Open speed.cloudflare.com. It reports download, upload, latency, jitter and the Cloudflare data centre you reached.
curl #
| COMMAND | DESCRIPTION |
|---|---|
curl -sS -o /dev/null -w '%{speed_download}\n' 'https://speed.cloudflare.com/__down?bytes=100000000' | Download speed in bytes per second (here a 100 MB transfer) |
head -c 5000000 /dev/zero | curl -sS -o /dev/null -w '%{speed_upload}\n' -X POST --data-binary @- https://speed.cloudflare.com/__up | Upload speed in bytes per second (5 MB of zeros) |
curl https://www.cloudflare.com/cdn-cgi/trace | key=value lines about your connection: IP, data centre (colo), country (loc), HTTP and TLS versions, and WARP and gateway state. No official docs page was found |
Multiply bytes per second by 8 for bits per second. A larger bytes value gives steadier results on a fast link.
Run Your Own Test Endpoint #
worker-speedtest-template is a Cloudflare Worker that serves GET /down?bytes=N and POST /up on your own domain, so you can test against your own Workers deployment. See Cloudflare Pages and Workers for deploying one.
JavaScript Library #
npm install @cloudflare/speedtest provides the engine behind speed.cloudflare.com. Its defaults use the public __down and __up endpoints, which the README marks as deprecated in favour of measurementTargets. The README does not say third-party use of the public host is supported, so point measurementTargets at your own Worker for anything automated.