Or a privacy respecting way on the web.
I am a big fan of MyNoise, which mixes real-life recorded sounds, but you have a ridiculous amount of control over almost everything.
It’s browser-based, so compatible with any device. Once it has downloaded the sounds, it doesn’t use any more bandwidth.
Definitely worth supporting with a donation.
The amazing thing is that one guy is behind everything you see and hear. Dr Pigeon is like a polymath. He develops and runs the site, creates all the sounds and plays all the instruments (with a few exceptions). I beg everyone who uses that site to donate, so he can keep going.
What exactly are you looking for? Why not just download one of those 24+ hours white noise videos from YouTube and play those with a media player?
I’m looking for something like Dark Noise on iOS, which allows you to mix different sounds and regulate their volumes.