Gerber Viewer appGerber Viewer is Science & Education tool that is open source under the GPL-3.0-only license.
Free and easy to use app for Gerber file viewing. How to use? Just add gerber file (one or more) from your device with "+" button and set it visibility with checkbox. Then go to next screen (navigate to screens with two toolbar buttons at the top of screen) and use common gestures for zoom and pan.