Amazon has coupon codes, I post them all the time, well okay it’s not Amazon that has the majority of them; sellers issue those bad boys. Not to say Amazon doesn’t have codes as well, but… I digress.
There is an entire section on Amazon devoted to coupons. Not manufacturer coupons, but coupons for products on Amazon. They range from a the average 5% or 10% off to as much as 90% off. From what I have seen the coupon availability is the same as most other deals, it is regional so you may have a coupon that someone else may not.
Where do you find those coupons? RIGHT HERE
The coupons are in addition to a Subscribe&Save discount or other promotions. You can pair a lightning deal with a coupon or a coupon code with the coupons.

How do I apply the coupons? You “clip” them. Under the price for the item is a green box, or green wording, that you then click (clip). The discount shows at final checkout.
You can also sort the coupons by category like Health & Personal Care, Beauty, and Office Supplies among a few.