We got fed up with either juggling multiple sets of screenshots or paying monthly for a fairly simple tool that then charged extra for different layouts. So we made Simple App Screens. A free, in-browser tool.
Everything runs in the browser, so your screenshots and content never leave your PC. There's no login, no subscriptions, no gated content, and you can export as many times as you want.
Projects are stored as a .sasb file, which is just a zip with the screenshots you upload and some JSON for the project.
Enjoy,
The GNK Softworks Team