geo-extent
Simple, Modern Geospatial Bounding Boxes
@math.gl/proj4
Proj4js wrapper for conversion between geospatial CRS (coordinate reference systems)
get-epsg-code
Gets EPSG Code for Various Inputs (incl. OGC WKT, ESRI WKT, GML, Mapfile, PROJ String, Proj4js String, XML)
proj4m
Handle transformation between mars projections.