—Mbps
Internet Speed Test
Measure download, upload, latency and packet loss against Cloudflare's global edge — 100% in your browser
✨ New🔒 Browser Only
Nothing leaves your browser
Ping
Download
Upload
Loss
READY
—ready
—Mbps
—ms
Ping (unloaded)
—ms
Latency variation
—%
Dropped during test
Loaded ↓
— ms
Loaded ↑
— ms
Spacestart / re-run test
## A speed test that actually respects your browser
Most speed tests lock you onto a single server, bury the numbers under ads,
or try to install a desktop agent. This one does none of that. It spins up
Cloudflare's open-source measurement engine — the same one that powers
`speed.cloudflare.com` — and runs it straight in your tab.
### What you get
- **Real bidirectional measurements.** Download, upload, unloaded latency,
jitter, packet loss, and **bufferbloat** (loaded-latency delta, which is
what kills video calls even on "fast" lines).
- **Futuristic gauge**, not a progress bar. 270° needle, glowing arc,
auto-scaling ceiling from 10 Mbps DSL lines up to 10 Gbps fibre.
- **Live sparklines** next to the download and upload cards so you can see
the connection stabilise instead of guessing.
- **Classification badges** (great / good / average / poor / bad) on every
metric using pragmatic thresholds — 300 Mbps earns "great", not 1 Gbps.
- **Anycast routing.** Cloudflare sends you to the nearest of 330+
datacenters, so the test doesn't flatter or punish you based on a
single far-away server.
- **No sign-up. No cookies. No apps.** Your IP is visible to Cloudflare
for the duration of the test — that's it.
### Why Cloudflare's engine?
Because it's open source (Apache 2.0), used at production scale, and
doesn't run on one company's shared cluster. It uses the browser's
`PerformanceResourceTiming` API, WebSockets and WebRTC to measure the
full round-trip — including the TCP slow-start ramp that most lightweight
tools skip over.
Hit **Start Test**, wait ~15 seconds, and you'll know exactly what your
ISP is giving you right now.
Frequently Asked Questions
Everything you need to know about this tool
For a browser-based test, yes. We use the same Cloudflare measurement engine that powers speed.cloudflare.com, which measures against Cloudflare's global anycast network (330+ POPs). Peak numbers match Ookla within a few percent on any decent home connection. For absolute precision you still want an Ethernet-connected desktop client, but no web tool will beat this one.
Bufferbloat is how much your latency balloons while the connection is saturated. A line can show 500 Mbps down and still be unusable for Zoom because latency jumps from 20 ms to 400 ms under load. We measure both, and flag the delta. If bufferbloat is "poor" or "bad", your router needs QoS / Smart Queue Management.
No. The test traffic flows directly between your browser and Cloudflare — DocTools is not in the path. We do not receive the numbers, your IP, or anything else. You can confirm in DevTools → Network: zero requests to doctools.cc during the test itself.
Because real networks are noisy. Wi-Fi signal strength, other devices on your network, the state of your CPU and the browser's own scheduler all introduce variance of 5–20%. For a reliable reading, run the test 2–3 times with other tabs closed and take the median.
Yes — the layout adapts to phones, and the engine works on any modern browser with fetch + WebSocket support. On cellular the test will obviously measure your mobile connection, not Wi-Fi unless your phone is on Wi-Fi.
Some workplaces block WebSocket traffic or the speed.cloudflare.com domain, which the engine needs. If you see an error and you're on a VPN or corporate proxy, that's usually why. Home and mobile networks almost never hit this.