I have several ecommerce clients, many of whom use ZenCart.

I've never had to directly interface with a client's accounting software. Many of my clients are probably 'too big' for Quickbooks, so they use something else. (MAS, perhaps)

However, since I never need to worry about it, I'm also not very informed, either.

Specifically regarding QuickBooks, I've never heard of a client directly integrating that software with a shopping cart. By 'directly' I'm referring to live integration, where order data is synchronized with Quickbooks in real time.

I know there is a QBI plugin for working with Quickbooks 'on demand' on a regular basis.

Is there something else out there? How do ecommerce stores typically interface with their accounting software?