AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.
AmzScope - Find profitable products for sale on Amazon in one click, relying on statistics instead of intuition
TrackChecker Mobile - TrackChecker Mobile app features tracking of parcels and online orders, so users don’t have to worry about losing a package by tracking the parcel right on their mobile phone screen.
Jungle Scout - Amazon product research made easy.
Track24 - Track24 app assists you in tracking the packages of more than 600 international courier and postal services from all around the globe.
AMZScout - AMZScout extension will help you make a decision about picking a niche based on the actual data, not intuition.