Noisli

“There's another site called Noisli, which is the one that I used for most of college, and that one also lets you mix your own ambient soundscape with white noise, pink noise, brown noise, babbling brooks, rain, all that kind of stuff, but unfortunately, after being very much free forever, they have recently went to a paid model, where now there's a free plan that you can, I think listen to for 90 minutes a day, but after that you have to pay, kind of a bummer.”