You can store your downloads in your account when you signup!
A pretty girl smirks as she holds up her iPhone 6 to show it too you. The iPhone 6 is in landscape view. It holds an image of 1334x750px. Your mockup will look perfect against the brick background and purple clad girl. This stage will work for any type of app.
Drag & drop not supported, but you can still upload via this input field: