After trying turf.js with plain ole leaflet and getting confused because the most basic stuff wouldn't work, I'm thinking that turf.js requires Mapbox.js and access token. Can anyone confirm or deny this??
Turf has no visualization dependencies at all. It does not require any map display, and works with raw GeoJSON data. For example, I often use Turf on my desktop (via Node.js) for running analysis that outputs the results to files I open in QGIS. The code runs 100% on your machine, so there are no access tokens or servers involved anywhere in the process.