QuickBooks Online

This app works quite well, though I had a bit of a challenge setting up. Sherwin helped me though and I was sorted out in no time - thanks!! I had a few other issues, and Lori helped me; customer service has been great, very quick and genuinely helpful!

The one downside is that inventory doesn't work for me to sync in QBO since QBO's inventory system isn't great, but Shopify tracks it well enough and we do have a specialty product/business, so it usually makes things extra complicated anyways.