Screenbuilder

Screenbuilder is a free tool for creating app store screenshots that look polished without manual size editing afterward. According to its site, the images it exports are high quality, and it targets creators who want simple results without design hassle.

Everything runs in the browser, and the site states that no images or processing happen on its server. Screenbuilder is positioned for creators who lack time for small design problems, and it is completely free to use for building store images.