Stack.app is described as 'Save and explore books and book stacks. Stack lets you easily record your reads, create your own digital stacks and explore other users' picks' and is an website in the news & books category. There are more than 50 alternatives to Stack.app, not only websites but also apps for a variety of platforms, including iPhone, Android, iPad and Android Tablet apps. The best Stack.app alternative is Goodreads, which is free. Other great sites and apps similar to Stack.app are Open Library, inventaire.io, LibraryThing and Tome.