View STL files online

What is an STL file?

STL is the standard file format for 3D printing. It describes the surface of a model as a mesh of triangles, with three corner points per triangle. It has no colors, textures or units. CAD apps such as Fusion, SolidWorks, Onshape, Tinkercad and Blender export STL, and sites like Printables and Thingiverse share models in it. STL comes in two flavors: compact binary files and larger, human-readable ASCII files. This viewer opens both.

How to view an STL file online

Drop an .stl file above. The model is read and drawn with WebGL in your browser, so even a large print file opens without installing a slicer or CAD app:

• Drag on the model to rotate it around its center. Use the mouse wheel or the zoom buttons to move closer.
• Switch between Solid, Solid + edges and Wireframe to inspect the triangle mesh and spot thin walls or very dense areas.
• Press Reset view to frame the whole model again.

Check dimensions, volume and triangle count

The panel next to the model lists its width, depth and height from the bounding box, in millimetres and inches, plus the triangle count, volume and surface area. STL files don't store units, so the viewer assumes millimetres, which nearly every slicer uses. If a part reads 25.4 times too small, it was exported in inches. Volume is accurate only for closed, watertight meshes. It gives a quick estimate of how much filament or resin a solid print needs.

Private by design

Unreleased product designs and client parts shouldn't go to an unknown server just to take a look. The STL is parsed by code running in this tab and the 3D view is drawn on your graphics card. The file never leaves your device. If you need the model in another app, Download OBJ saves a copy as a Wavefront OBJ.

Before you start

Input: STL. Output: 3D preview and OBJ. The settings appear before anything runs, so you can check them first. Your original file is never changed.

These formats often follow rules set by one app or device. Test the result where it will be used, and keep the source in case you need to export it again.

Keep the original until you have opened and checked the result. The work happens in this browser tab, so the size you can handle depends on your device's memory, your browser and the file itself.

How to view STL files online

1. Drop an .stl file into the box above, or browse to pick one.
2. Drag to rotate the model and scroll or use the buttons to zoom.
3. Switch to wireframe to see the mesh, and read the size in the side panel.
4. Download an OBJ copy if another app needs that format.