It does much of what the more complex software does: measure distance, surface areas, perimeters, angles; markup; takeoff (count & run lengths), ...etc. I even built an overlay feature to compare two pages.
In this age of AI, I think simple software such as this can only ever be free. How do you offer a web app for free? Make it local only. I think there is a lot of space to explore in local-first web apps.