On-Screen Ruler - lightweight, free, semi-transparent ruler
PackageX Receive - PackageX Receive digitizes package-receiving operations and delivers world-class package management solutions.
Meazure - What are the dimensions of that image? How big is this window?
AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.
Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.
DelivApp - Software for managing online ordering, delivery and loyalty for multi-unit restaurants