A web app to make a random background for websites https://saar-janak.netlify.com
This is a relative simple web application that will draw a background using JS that the user can use for website backgrounds, desktop wallpapers or whatever their heart desires!
Find the hosted web app here
This is licensed under the generous MIT license, so feel free to use it for your own purposes!
For the time being there is no way that I know of to make the images available to you through the web application, so instead I'd reccomend using a screenshot tool.
While I have no idea what is available on Windows or Mac, on Linux there is a handy program called Shutter that I like quite a bit. Shutter enables you to take a screenshot based on a selection of your screen, enabling you to use the background on your sites.
There are several additional options for Linux as well, such as Flameshot and most browsers now come equipped with their own screen capturing programs. So pick your poison and get to making some killer web sites.