Command line tools for converting VOX to SVOX and SVOX to GLTF are now available here: https://github.com/jel-app/svox-tools
NPM Package: https://www.npmjs.com/package/smoothvoxels
This is an optimized and npm packaged fork of the Smooth Voxels library by Samuel van Egmond.
It has been updated to use Typed Arrays and bitfields which results in a 5x or so speedup. All features from the main project are supported.
A copy of the Smooth Voxel Playground using this library can be found here:
https://gfodor.github.io/smoothvoxels/
Full documentation can be found here (which applies to both libraries, other than the section on Shells)