What are the shortcuts for the background generator?
z previous background
x next background
v vary current background
e export current background
esc close export menu
How can the backgrounds be saved?
Click the share button. It's a link, so ctrl+click or middle click on the share 'button' works as well. From there you can either export the background as a free lower resolution PNG image or pay for the selected resolution as a PNG or vector image (SVG).
How does copyright apply to the generated images?
All the images you generate with this (web)application are under your copyright. Just like other applications such as Adobe Photoshop, Inkscape or Krita.