I have to present my own app here: Rain Rain for iOS and Android. Lots more than just rain, easy to use, and doesn’t require any kind of sign up or email. Let me know what you think! www.rainrainapp.com /

Naturespace and Rain Rain. The former for rainfall which is essentially white noise and the latter for a washing machine that covers the lower frequencies. It’s great for blocking sound if you live in a busy area.