An open source and free screen pixel ruler based on C#/.Net Core 3.1 that is a clone of the application MioPlanet PixelRuler. You can read the help from the MASTER branch
I was using MioPlanet PixelRuler for pixel precise measuring of user interface spacing and found that it was lacking some quality of life features. The utility is quite dated and I needed the ability to freeze the ruler measurements, shift the start of the ruler to the current cursor position and flip the hatch markings.
I decided that I should write my own one based on the .NET framework and open-source it. The first version was written in Visual Basic.Net and based on the .NET Framework 4.5. This new version is rewritten from the ground up in C# and based on .NET Core 3.1.