QMK Web Configurator
QMK Official Web Configurator
QMK Configurator is the official online tool used for remapping keys and creating firmware file for QMK keyboard.
You can follow the instructions laid out in this blog post to get started with QMK official web configurator.
X-Bows Knight Plus
X-Bows Knight Numpad
(Note: When you update the Knight Plus numpad firmware, your USB cable should be plugged into the numpad and the corresponding numpad firmware should be used. Press Fn+Esc on the numpad to enter DFU mode.)
The QMK web configurator is less convenient than Vial and Via if you remap keys frequently, because you need to flash the firmware every time you remap keys. If you flash the Vial-compatible or Via-compatible QMK firmware once, you can remap keys in the GUI software and don't need to flash the firmware every time you remap keys.