Fully web based serial terminal using Serial Web API - Access your serial / USB-Serial device directly from the browser!
Working example:
https://bipes.net.br/aroca/web-serial-terminal/
August/2021: Works on Google Chrome and MS-Edge without the need of any special option. Still not available on Firefox.
When using on a webserver, due to security restrinctions Web Serial API will only worked if served from an HTTPS server. If deployed to HTTP, the connect button will be disabled.