The data on FindNiche upgrades on hourly basis, so you always can catch out the trending niches and make the right decisions. It also serves with different filters, so it's quite user-friendly, especially when you find to search out some products related to some specific categories or countries. All in all, just try it out.
AliShark - Usually, you only see those top-selling products, leaving those hidden gems behind. With Alishark, It doesn't have to be a top seller to be spot anymore.
Sensor Tower - Sensor Tower is a platform for app store optimization and app industry intelligence.
Ecomhunt - Ecomhunt allows you to easily find products that are already proven to sell or how we like to call them Winning products! - in only a few clicks - it's time to stop guessing, start selling!
App Annie - App Annie is a marketing analytics tool available for apps of all kinds. With App Annie, you can track sales, traffic, and a variety of other factors pertinent to monitoring an app's trajectory.
AliInsider - Find Most Profitable Dropshipping Products in a Click! Analyze Competition, Check Saturation of Any Product, Find Top Suppliers & Target Markets.
appfigures - Cross-platform app store analytics for all of your mobile apps.