Stack N Pack

I recommend the latest version rewritten, faster, easier to use, and supports UV Tile workflows.
https://phillipjenne.gumroad.com/l/stacknpackplugin

If you need to run on an older version of Painter, you're in the right place.

Stack N Pack is a plugin for Substance Painter 2018.2.2+. With a friendly UI, customize your export presets and quickly export your textures and even merge multiple texture sets together into a single image set, all without leaving Painter. Easy drag and drop install for both Windows, macOS, and Linux.

Newer versions of macOS have stronger security settings that may prevent the plugin from working, and may require running the python in a local setup rather than through the compiled python.