Free online STL viewer

Open STL files right in your browser: rotate, zoom, and check dimensions, volume, and watertightness. Nothing is uploaded, your file stays on your device.

How the viewer works

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. The panel below the viewer reports exact dimensions, volume, surface area, triangle count, and whether the mesh is watertight.

STL files hold plain triangles with no units and no color. The viewer assumes millimeters, the convention slicers and every printable model site use, so the dimensions below match what your slicer will show.

Frequently asked questions

Does my file get uploaded?

No. The file is parsed and rendered in your browser with three.js and WebAssembly. It never leaves your device, and the viewer keeps working offline once the page has loaded.

Why does the size look wrong?

Mesh formats like STL don't store units, so the viewer reads the raw numbers as millimeters. If a model was exported in inches it shows 25.4 times too small; glTF files use meters and can look 1000 times off. The scale tool fixes both in one click.

Can I edit the model here?

The viewer is for inspecting. For quick fixes use the free repair, scale, split, and convert tools linked below. For real changes, like resizing a hole or adding a mount, type what you want in the box under the viewer and the GrandpaCAD chat takes it from there.

Viewers for other formats

OBJ viewer PLY viewer GLB viewer glTF viewer 3MF viewer STEP viewer 3DM viewer All-format 3D viewer

More free 3D file tools

View a model Repair a model Reduce file size Convert 3D files Measure a model Scale a model Split a model Mirror a model Print weight & cost

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