⚡ Fast — Local Speed Test

A self-hosted internet speed test that runs entirely on your own machine.
No third-party servers, no tracking, no ads.

Requirements

Pick whichever runtime you have — no extra packages needed for either:

Runtime	Minimum version
Python 3	3.6+ (built-in on macOS/Linux)
Node.js	14+ (no npm install needed — uses only built-ins)

Run

Python:

python3 server.py

Node.js:

node server.js

Both open at http://localhost:3000.
Use a custom port if needed:

python3 server.py 8080
node server.js 8080

How it works

Phase	What happens
Ping	10 small HTTP requests → measures round-trip latency
Download	Server streams 1 GB of random bytes → browser measures throughput
Upload	Browser sends 512 MB of random bytes → server measures throughput

All traffic stays on localhost.
The download/upload payload sizes can be tuned at the top of public/app.js (CFG.dlSize / CFG.ulSize).

Stop

Press Ctrl + C in the terminal.