geodesy
Libraries of geodesy functions
tsgeo
TsGeo provides abstractions to geographical coordinates (including support for different ellipsoids) and allows you to calculate geographical distances between coordinates with high precision.
node-vincenty
Calculates the distance in meters between two latitude and longitude coordinates.
@panaaj/sk-geodesy
Subset of libraries of geodesy functions from http://www.movable-type.co.uk/scripts/geodesy-library.html modified for use with Signal K server plugins