Keepa

Keepa maintains price histories for all products on Amazon, the worldlargest and most trusted online merchant. Users can individually track the price development of products they are interested in, and Keepa will notify them when the price has reached a predetermined threshold. Besides this tracking feature, Keepa can also be used to browse the full range of Amazon goods, making use of the clear and well laid out Keepa interface as well as great money-saving search features such as Daily Drops.