Written in Go with target WASM/WASI.

Watch the live demo on ports.sh

The WASM main function scans all the open ports in the specified range (see main.go), via 0.0.0.0 with no-cors fetch mode in Javascript level.

• Discovers any TCP open port available on the visiting host.
  
• One byte of response / filtered port is enough
• Scans TCP only (WASM has no UDP support yet)
• Uses golang 'http' API rather then 'net' API (better browser compatibility)

Please see ./build.sh

Simply start an HTTP server locally, for example:
python3 -m http.server 5000
Or:
npm i -g serve && serve