Slick tool. There are scenarios where this does work and work well (e.g. static layout) but for responsive web layout design involving transitions this falls a little flat.

This looks like a neat tool, with a nice simple solution to a common UI development problem.

What image file formats can be used as mockups?

Pretty much any image format OSX supports.

Thanks for making this - seems to work with PSDs so that's great. This tool has already saved me a bunch of time this week!

One feature request would be to make the app automatically refresh the overlay when the source file changes, or to have a keyboard shortcut to refresh from the saved file. This would be useful when toggling layers on/off in Photoshop to look at different states of a screen. Cheers!

Any Linux alternative to this? Nice work.

Windows version plix. :(

Amazing! Nice work!