ALTO is used at run time in 4 crates (of which 1 optionally). It is a direct run-time dependency in 2 crates. It's used only as a dev dependency in 1 crate.

Depender (with downloads and own rev deps) ALTO version
spectra ^3.0
1 keeshond_audio ^3.0.4
102K 34 lewton dev ^3