One Click Upsell ‑ Zipify OCU

This app really increased my AOV, and it does everything I could ask for from an upsell app plus a lot more! The best thing about it is you can do split-testing, something that is very hard to find. It has post purchase, pre-purchase, and thank you page offers, you can do more than one post purchase and you can do down-sells. Also has a neat dashboard where you can see which products are doing good. Very user-friendly, any one can use it. If you need help, you can watch one of their many training videos or simply reach out to their support team and they can answer any questions.
I'm never going to look any further for an upsell app!