Connecting Opencart website to Laravel based Accounting Software

We have Opencart Website and Laravel based Accounting and Billing Management Software(Web App). We want them to be synchronized, if any billing is done on Billing Software, the product stock should decrease on Opencart and Billing software, in both the place.
In the same way, when we receive orders online, the stock must be reduced in the billing software. And Billing Software should also have a list of Online orders.