You can store your downloads in your account when you signup!
Use this mockup of a woman is hanging out with her friend, holding up an iPhone 6. She is holding the iPhone 6 mockup in portrait view. Sitting to her right is her friend relaxing on a couch. The iPhone 6 mockup holds an image of 750x1334px. This is a great place for a social or casual app.
Drag & drop not supported, but you can still upload via this input field: