STL is the most common file format for 3D printing. It describes a model’s surface as a mesh of triangles, with no colour or texture information. Because it is simple and universal, almost every 3D printer and slicer accepts it, which is why STL viewers are so widely used.

Does the size shown match my printer’s units?

The viewer reports the model’s bounding-box dimensions in the units the file was saved in, which for STL is almost always millimetres. So a reading of 60 × 40 × 20 typically means 60 mm wide. Check against your slicer if a model looks unexpectedly large or small.

How do I move the camera around?

Drag with the left mouse button to orbit around the model, scroll (or pinch) to zoom in and out, and drag with the right mouse button to pan. The Reset button reframes the model if you lose it, and Spin rotates it for you.

How big a file can it open?

The viewer can handle large models, with the practical limit set by your device’s memory and graphics, not by us. Very heavy meshes (tens of millions of triangles) may load slowly or strain a phone, but typical models open quickly on a normal computer.

STL Viewer

Open .stl files in your browser and inspect them for 3D printing. Drag in an STL to rotate, zoom and pan, switch to wireframe, read its real-world dimensions and triangle count, and save a screenshot. Nothing is uploaded.

No upload, opens locally
100% free
No sign-up, no app
GLB, GLTF, STL, OBJ, PLY
Private, stays on your device

Read the guide: How to View an STL File

Drop a STL file here

Or . Your file opens locally and is never uploaded.

How to use it

1
Open your model

Drag a file onto the viewer or click Open model. It loads straight from your device, with nothing uploaded.
2
Orbit, zoom and pan

Drag to rotate, scroll to zoom, and right-drag to pan. Turn on Spin to rotate it automatically, or Wireframe to see the mesh.
3
Inspect and capture

Read the triangle count, vertex count and dimensions in the info bar, then save a PNG screenshot of the current view.

When it comes in handy

Check a print before slicing

Preview an STL and confirm its size and shape before loading it into your slicer.

Verify a download

Quickly look over an STL from a model site to see it is the part you wanted.

Measure the bounding box

Read the dimensions to check the model will fit your printer’s build volume.

Opens locally & 100% in your browser

Your model is read and rendered right here on your device. The file is never uploaded to a server, there is no sign-up and no size limit beyond what your browser can handle, and any screenshot you save is generated locally too.

Frequently asked questions

What is an STL file?: STL is the most common file format for 3D printing. It describes a model’s surface as a mesh of triangles, with no colour or texture information. Because it is simple and universal, almost every 3D printer and slicer accepts it, which is why STL viewers are so widely used.
Does the size shown match my printer’s units?: The viewer reports the model’s bounding-box dimensions in the units the file was saved in, which for STL is almost always millimetres. So a reading of 60 × 40 × 20 typically means 60 mm wide. Check against your slicer if a model looks unexpectedly large or small.
How do I move the camera around?: Drag with the left mouse button to orbit around the model, scroll (or pinch) to zoom in and out, and drag with the right mouse button to pan. The Reset button reframes the model if you lose it, and Spin rotates it for you.
How big a file can it open?: The viewer can handle large models, with the practical limit set by your device’s memory and graphics, not by us. Very heavy meshes (tens of millions of triangles) may load slowly or strain a phone, but typical models open quickly on a normal computer.