ViscoSoft

This app is absolutely fantastic. With the ability to use workflows with subworkflows and hit Shopify's API, you can automate just about anything within Shopify. Bonify has built an awesome app and whenever I've had questions, their team has been quick to respond. If you're having issues on the back-end related to fulfillment, notifications, order tagging, or anything back-end related that Shopify doesn't solve exactly the way you need it to, this app can help you do it.