I like this, but my suggestion is to give the units the measurements are in. I assume it’s millimeters. Also, it may be worthwhile to give the ability to change units from metric to standard.

First time I opened a file it wasn’t oriented right and I could not see most of it. Second time, it was centered in the viewport. Seems OK, just basic surfacing options. No menu items (like for Open File). Can’t drag and drop a file into the window to open it, or onto the icon. That is BASIC Mac functionality stuff. The “cloud” icon is for open, that doesn’t make sense. View buttons on the bottom don’t close their menus, you have to click in the window to hide them. OK, easy to try options, but clicking the button again doesn’t close them. No way to zoom in/out.

I like this STL viewer but it needs a button to position (move object) the views. It can be difficult to adjust with fingers. The icons make little sense. The ruler icon shouldn’t be to make finish rough or smooth. Should be to measure things or show dimensions. The dimension screen needs to show measurements in a fix manner. Flipping the object around creates backward views of numbers.

Doesn’t load completely every time. It’s hard to maneuver objects when they do load. No reference point for center. Very limited zoom out. And will freeze every time when in the editing mode (pen tip).