You can use Photoshop, Sketch, etc. to make those. Just need to make sure they can be tiled, or seamless. Same with code, you have to match the font-color very closely to the background, so it's really subtle.
toptal.com/designers/subtlepatterns/ has tons of those.
Whoo, Subtle patterns, cool resource!
As for tools, I use Affinity Designer on Windows... don't want to pay subscription fees... 😛
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.