Amazon

Caplena

Sorts reviews into themes; built for teams, solo you use a slice of it

Helium 10

Product research, keywords and listing tools for Amazon sellers

Jungle Scout

Product database and sales estimates for Amazon sellers

Keepa

Shows the price history of any Amazon listing over years

Perpetua

Runs marketplace ads to a target instead of by hand

sellerboard

Shows real profit per product instead of just revenue