Coupon extensions like Honey and Capital One Shopping (formerly Wikibuy) have been around for a while and are rapidly growing their user bases. While they hold the potential to help increase conversions, they pose a major threat to online retailers' profits and ability to control their own discounting/coupon strategies.
Recently, we had an experience that highlights just how dangerous they can be when someone on our team was able to get 100% (!!) off of their purchase from a well known clothing retailer through a coupon they found on Capital One Shopping.
Here's the story of how it all went down, along with the solution we're building to prevent it from happening in the future: https://www.clean.io/blog/coupon-extension-100-percent-discount