Priceva
7.3#4 in competitor price monitoring softwareFrom $99 a monthFree planWebAPI
VisitPriceva suits e-commerce retailers and brands that need to follow competitor prices, stock, discounts, and MAP or MSRP compliance. Its free Starter plan can suit monitoring needs limited to 20 products and 20 competitor sites.
You want what its maker publishes above — check its page for the details.