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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.
I love this site. I've been using it for a great many years.
what an amazing site - thanks!
This helps! Thanks a lot
While this may not be the thing you're looking for, it is easy to create your own noise with VCV Rack. You can record noise that you like and transfer it to your device of choice, completely free.
It is also a very powerful music production tool but it is lightweight and fairly easy to use for noise.
VCV rack is awesome, if not the easiest to start from scratch with. For those who haven't heard of it, it's basically a virtual modular analog synthesizer. You can build your own sound generating machines out of a huge selection of modules, including oscillators, filters, sequencers, etc. Some of the modules are based on real hardware modules that you can buy, but there's a huge variety.
It's fun to play around with, but if you're new to modular synthesis then I recommend limiting your module selection to just the built-in ones to start because the full selection is pretty overwhelming if you don't know a VFO from an ADSR evelope generator.
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.
Using Freetube (a youtube privacy frontend) you can listen to white noise.
Baby sounds
Easy noise