Shopify Marketplace Connect

Barely works for Etsy. I can't speak to the other integrations because I only connected Etsy and had a bad experience.

If your Etsy listings are exactly the same as your shopify products, this app will sync purchases. However, it will not sync any discounts that the customer applies on Etsy so it makes all analytics on Shopify useless. It also will not sync any personalization data from Etsy. I was able to do some matching using SKU, but it still didn't work great. If you complete the order on Etsy, it will not sync the data to Shopify.

I could have made this work were it not for the discounts not being reflected, but after having contacted support several times with no solution, I have given up.