Source of the HD WEB backgrounds for 4K and higher screens on the rise

Vladstudio

Free for lower resolution images, $14.99 for a premium membership

Offering everything from cartoons and celebrities to “motors,” music, nature and “vintage” backgrounds

Free in the “free” gallery, but most artwork is membership-based.

Free backgrounds, resolutions running up to the 4K TV spec (3840 x 2160)

Does not support the Retina MacBook Pro 2560 x 1600 or 2880 x 1880 resolutions, but supports the the Retina iPad and iPad Mini (2048 x 1536).

Free 2880 x 1880 backgrounds

Google’s search tools / Larger then 4PM