Meazure - What are the dimensions of that image? How big is this window?

Codezero - Collaborative Local Microservices Development

ScreenRuler - ScreenRuler lets you measure objects on your Ubuntu desktop using six different metrics.

LeadMD - LeadMD is the revenue performance consultancy that cuts through the BS by making your vision actionable and your outcomes measureable

Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.

Sirius - An open-source clone of Siri from UMICH