Jungle Scout - Amazon product research made easy.
Webgility - Accounting, Bookkeeping and Inventory Automation for Retailers & Brands
AMZScout - AMZScout extension will help you make a decision about picking a niche based on the actual data, not intuition.
CrazyLister - Create Better eBay Listings
AmzScope - Find profitable products for sale on Amazon in one click, relying on statistics instead of intuition
Multiorders - Shipping and Inventory Management Software is easy way to save time.