Free online glTF 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.

A .gltf file is JSON that often references separate .bin and texture files. The viewer reads the geometry and materials it can reach; if your model needs its sidecar files, convert it to GLB first so the textures come through.