Hi there,
We just launched a new App, the "Thank You Coupon" App. It let you give coupon codes to your customers after they make a purchase. This can highly increase your customer retention. You can fully customize the PopUp and no coding is required. Here is a demo:
https://checkout.shopify.com/9280822/checkouts/65f43e0b5f402cb2c75481c0d6efbd3a/thank_you
You can try the App here: https://apps.shopify.com/thank-you-coupon
If you have any feedback, we would really appreciate.
Cheers
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Webyze