Our store utilizes two apps from MKP Software... this SHOPLINK INTEGRATOR as well as a "QB-POLLER" app. The integrator app allows us to take data from Shopify and create physical sales receipts, sync financial data, and update inventory values from Shopify (online orders) into our Quickbooks point-of-sale. Then the poller app updates all of our inventory amounts (from hundreds of "in-store" brick and mortar sales) into our online store. This all happens practically in real-time.
Both apps have been irreplaceable for us and the support from their technician (Tim) has been phenomenal. We've only had a couple of bugs to work out given our very unique needs; but everything has been set-up and perfected both seamlessly, professionally, and in a timely fashion. The apps not only save us countless hours by integrating hundreds of transactions between both programs... but the apps have drawn business to us in unforeseen ways as well (such as letting our LOCAL customers know first-hand when a popular item is getting low in stock). This has therefore drawn business to us in the physical sense too. Very impressed with both apps. Definitely worth the expense and very reasonably prices as well!