Cuprum (Community Edition)

Cuprum is a multi-layer Gerber and Excellon viewer for the Mac platform.

It supports viewing (and printing) multiple layers at the same time.

A QuickLook plugin is integrated in the app, so you can preview files in the Finder and other apps.

Features:
-Reads Gerber and Excellon files
-Supports Gerber X2
-Measurement tool
-Cuprum allows full zooming and navigation of the image with an intuitive interface whether you use a trackpad, magic mouse, normal mouse or pen tablet.
-It can also zoom to actual size, which corrects for different monitor DPI’s, so actual size is actually actual size.
-Print out (or PDF generation via the print panel) is supported with variable scaling and presets for actual size and page fill.
-A QuickLook plugin is integrated which allows Finder to show a preview of a document.

***This Community Edition has limited functionality. A full version is also available***

The full version offers these additional features:
-Multi page print jobs
-Snapping with haptic feedback
-Transparent viewing mode
-The full version also includes All, Dimmed and Grayscale single layer modes, in addition to the Single and Monotone modes of the Community Edition.
-You can also import color sets for the layers, the Community Edition can only export them.