Essential Goods - Know immediately when an essential you need is back in stock
OctoShop for Chrome - Compare prices and get alerts when things are back in-stock
HotStock - HotStock is an all-in-one real-time product tracker for you that allows you to find the right product, exclusive deals, and discounts from all the major online stores.
Shopper.com - Uber for Coupon Codes
Avast SafePrice - Avast SafePrice is one of the leading online services that provide buyers with information about the latest price comparison of the products, deals, and discounts, and coupons.
Anakin - Get live pricing data of your competitors as an API