Apple - Is there an OS X application that overlays a grid onto the screen?
The xScope app is a veritable powerhouse of overlay, measurement and screen detail functionality.
You should be able to set up multiple grid lines if that is what you want.
- http://xscopeapp.com/guide#guides
This app has paid for itself tenfold over the years. Super useful for color and measurement and, of course, grids.
Red Line Tools is a free app which allows you to add various elements to the screen, such as: lines, grid, layout, and various image overlays on top of all windows.
