Ad Badger - Amazon PPC tool for optimizing campaigns
Gumroad - An all-in-one solution to sell your work and grow your audience.
Sellics - Sellics helps you to boost Your Amazon sales.
Payhip - Sell digital downloads, courses, coaching, and more from one simple platform.
NinjaSEM - PPC management software
Helium - Helium lets you accept payments by credit card for anything you want to sell online.