Perlin noise is great. processing has a decent implementation:
https://processing.org/reference/noise_.html
https://processing.org/reference/noiseDetail_.html
My one pet peeve is that it doesn’t allow you to control individual octaves. And, although the value is always between 0 and 1, for many settings the outputs are more constrained than that.
If I ever get a chance to take a real sabbatical, working on a library for precisely shaped noise would be high on my list.
+1 for
dsp