Coordinate system. Upload a single band DEM in geographic WGS84 (EPSG:4326). The viewer reads the bounding box and builds the block at true horizontal scale, so the relief looks right before you add exaggeration.
Projected files. A UTM or other projected raster still renders, but the lat/lon read out assumes degrees. Reproject to EPSG:4326 first for accurate results.
Big rasters. The DEM is decimated for a smooth preview and decoded across CPU cores. Keep full resolution mesh on export turned on to rebuild at the native grid.
Controls. Left drag to orbit. Right drag to pan. Scroll to zoom, or two finger drag on a trackpad. Hover the surface to read coordinates.
Privacy. Everything runs in your browser. Your DEM and settings are never uploaded, never stored on a server, and nothing is kept after you close the tab. Use Save Project to keep a copy as a local file.
Free global elevation downloads. A single-band GeoTIFF in EPSG:4326 works best here.
Tell the tool which columns hold the coordinates.