Sage & Sill
Setup was a breeze, integrates with Shopify's edit order API, and lets you use smart auto-upsells with Shopify's product recommendations. The upsell pop-up looks clean and legitimate, not gimmicky or spammy. Did I mention the monthly price is a STEAL compared to the bigger upsell apps? This might end up being my new go-to conversions app. Kudos to Digismoothie, 10/10!
Finally a post-purchase upsell app which does not create a second order, but edits the order and charges the customer that way! Perfect for anyone looking for upsells that make sense and just work.