Squared Inc. provides two API modes, which differ in performance and feature sets:

highload.api.squaredinc.co (Default) - default API endpoint for create_invoice operation. It is designedto support high loads of up to 1000 requests per second at greater speed.

api.squaredinc.co - legacy and more compatible API endpoint that is used for webhook verification and retrieving information about invoices, it is planned to migrate these capabilities to highload.api.squaredinc.co in the coming weeks