About GeoDrafter

GeoDrafter is a set of free map tools that run in your web browser and measure on the real shape of the Earth.

Why it exists

Many online map tools draw on a flat web map and measure in its projection. That looks right on the screen, but the numbers drift as you move away from the equator: a "100 km" circle drawn flat in the Web Mercator projection covers only about 50 km on the ground in Oslo or Anchorage. GeoDrafter does the maths on the WGS84 ellipsoid, the same model GPS uses, so the answer is the same wherever you are.

How it works

• Calculations: GeographicLib by Charles Karney, the reference implementation for geodesics on the ellipsoid (accurate to about 15 nanometres).
• The map: MapLibre draws it, and the background map comes from OpenFreeMap with data from OpenStreetMap.
• Place search: a list of towns and cities from GeoNames, searched in your browser.

What you draw stays in your browser and in the page address (the part after #, which browsers do not send to the server). Copy the address to share it. All sources and licences are listed on the data sources page.

Who is behind it

GeoDrafter is built and run by Henrik Rosenskjold, a GIS specialist from Denmark and owner of the consultancy GISkon. Working with coordinate systems, projections and spatial data every day, he wanted simple map tools that get the geodesy right and explain their limits honestly.

Every tool has automated tests that check the results against GeographicLib and known values, not just that the page loads.

The sister site FileReshape converts map files (KML, GeoJSON, shapefile, GPX and more) in your browser.

Company details

GISkon, sole proprietorship (enkeltmandsvirksomhed)
Owner: Henrik Rosenskjold
CVR: 38755986 (Danish Central Business Register)
9400 Nørresundby, Denmark
E-mail: [email protected]

Questions, bug reports and ideas for new tools are welcome on the contact page.