Billbee

I have been using Billbee for over a year to integrate 3 sales channels and 2 fulfillment providers. Billbee provides some automation but also has a good REST API for any custom tasks. Except for some fields in the API that are not writable, everything works great and fits my needs perfectly. Staff respond quickly to questions and issues. One thing I appreciate most is that the price is capped at a very affordable amount.