https://www.webull.com/ is for the international one
https://www.webull.hk/ is for the Hong Kong one
doc: https://developer.webull.hk/api-doc/
order request doc : https://developer.webull.hk/api-doc/trade/order/place-order
Tested Environments:
UAT Environment:Error
Production Environment:OK
to play around, better get a list of instruments and their id first.