Free online IGES viewer

Drop a file and it renders instantly: drag to rotate, scroll to zoom, right-drag to pan, and toggle wireframe in the corner to see the triangle structure. Files that carry materials and textures, GLB and glTF, 3MF, 3DM, and colored PLY scans, render with them; the textures button switches back to the plain mesh. The panel below the viewer reports exact dimensions, volume, surface area, triangle count, and whether the mesh is watertight. Drop another file onto the viewer at any time to swap the model without reloading the page.

IGES (.iges / .igs) is the older CAD exchange format, still what a lot of legacy Pro/ENGINEER, CATIA, and NX data ships as. The viewer tessellates its surfaces with Open CASCADE in your browser. Files that hold only wireframe curves have no surfaces to display and will come up empty.