CoordMapDefault workflow: WGS84 → Web Mercator. Choose input/output CRS (WGS84, EPSG:3857, UTM auto-zone, national datums, or GCJ-02/BD-09), paste one point per line, convert, then copy or export. UTM lines use easting,northing,zoneHemisphere (e.g. 449345.06,4417292.49,50N).
Lets you move lists of coordinates between GPS (WGS84), web maps (Web Mercator metres), UTM survey grids (EPSG:326xx/327xx), and common national datums—without desktop GIS—so metre-scale mistakes from mixing CRS are avoided.
Web Mercator and UTM use standard WGS84 ellipsoid formulas in the browser. GCJ-02/BD-09 use the gcoord library. NAD83, ETRS89, GDA2020, JGD2011, Korea 2000 and SIRGAS2000 are shown as geographic lat/lng compatible with WGS84 for web display. Confirm the EPSG code expected by your GIS before surveying use.
It batch-converts coordinates between WGS84, Web Mercator (EPSG:3857), UTM (auto zone), national datums (NAD83, ETRS89, GDA2020, JGD2011, Korea 2000, SIRGAS2000), and China-specific GCJ-02 / BD-09. Conversion runs locally; nothing is sent to a geocoding API.
WGS84 is what GPS and most APIs return (degrees). Web Mercator is what slippy map tiles use (metres). That pair is the most common web-mapping conversion.
When converting to UTM, the zone is chosen from longitude and hemisphere from latitude (north EPSG:326xx, south EPSG:327xx). When converting from UTM, include the zone in each line as easting,northing,50N.
They are listed for overseas workflows and labelled with their EPSG geographic codes. For web display they are treated as WGS84-compatible lon/lat; for centimetre surveying use dedicated software or NTv2 grids.
They are China-specific encrypted systems. Overseas projects usually stay on WGS84 / Web Mercator / UTM / local datums; China map SDKs need GCJ-02 or BD-09.
Geographic inputs are longitude,latitude. Web Mercator is X,Y metres. UTM is easting,northing,zone. Swapping axes places points in the wrong hemisphere.