Metalsmith - An extremely simple, pluggable static site generator.
Noisli - Noisli is a fantastic background noise and color generator for working and relaxing. Online soothing ambient sounds like White noise, Rain and Coffee Shop.
Nikola - Nikola is s static site generator tool written in Python.
Noizio - Feeling that the noise of the big city is too much for you to bear?
GatsbyJS - Blazing-fast static site generator for React
A Soft Murmur - Ambient sounds to wash away distraction.