The Web485 board works as a standard USB-to-RS485 adapter, but with WebUSB support.
The WebUSB JavaScript API allows web-based applications to access USB devices. WebUSB is supported by the Google Chrome browser and is also included in the Chromium open-source browser builds. If you are using Chrome (or a Chromium-based) browser, your web pages will be able to access RS485 devices connected to the Web485 board.
Tibbo is making extensive use of the WebUSB functionality. The first example of the Web485 board's usefulness is our web-based test application for RS485 Modbus Sensors (Bus Probes). There is also a generic PuTTY-like terminal app called WebTerminal.
To aid in the development of web-based apps (HTML pages) supporting the Web485 board, we offer an easy-to-use WebSerial library.