Free for use for any purpose. Under every picture there is a link from where you can download image with full resolution and quality.
https://th3r3v3nan7.deviantart.com/art/Abstract-Fractals-Wallpaper-724599615
https://th3r3v3nan7.deviantart.com/art/Fractals5-724656247
These pictures are from my portfolio on deviantart and are absolutely free to use for any purpose.