Most solutions that sync accounting software to HubSpot are pricey, and there’s a real reason: QuickBooks Desktop has no REST API. The company file sits on a local machine, so there’s nothing for HubSpot to call. The only route in is the QuickBooks Web Connector, which ships with QuickBooks and polls outward on a schedule using qbXML.
Disclaimer: I’m an accountant and I built this myself after getting tired of re-keying invoices by hand. Free during beta (I am not asking you to buy anything). One-way for now customers, invoices, and payment status from QuickBooks Desktop/Enterprise into HubSpot. Single-currency files only.
demonstration: https://youtu.be/TLPCIudfONo
Happy to answer questions on the mechanics.