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 units?

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

Is my STL uploaded, or does it stay on my device?

It stays on your device. The .stl is opened and rendered locally in your browser and never sent to a server, so a client part or an unreleased design stays private. There is no sign-up and no upload.

How do I rotate and measure the model?

Left-drag orbits the part, scrolling zooms, and right-drag pans it. The info bar shows the width, height and depth plus the triangle count, and Wireframe lets you check the mesh for gaps or overly heavy detail.

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.

Open an STL file in the browser to inspect an STL before printing, without waiting for your slicer to load. This free STL viewer reads the .stl from your device and lets you rotate, zoom, pan and switch to wireframe. Read the real-world dimensions and triangle count to check the part fits your build plate, then save a screenshot. Nothing is uploaded, so downloaded and in-progress prints stay on your machine.

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 STL

Drag a .stl file onto the viewer or click Open model. It loads straight from your device, with nothing uploaded.
2
Turn and measure

Drag to rotate, scroll to zoom and right-drag to pan, then switch to Wireframe to look at the triangles.
3
Check size, screenshot

Read the real-world dimensions and triangle count to confirm the part fits, then save a PNG.

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 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 units?: The viewer reports the bounding-box dimensions in the units the file was saved in, which for STL is almost always millimetres. So a reading of 60 x 40 x 20 typically means 60 mm wide. Check against your slicer if a model looks unexpectedly large or small.
Is my STL uploaded, or does it stay on my device?: It stays on your device. The .stl is opened and rendered locally in your browser and never sent to a server, so a client part or an unreleased design stays private. There is no sign-up and no upload.
How do I rotate and measure the model?: Left-drag orbits the part, scrolling zooms, and right-drag pans it. The info bar shows the width, height and depth plus the triangle count, and Wireframe lets you check the mesh for gaps or overly heavy detail.

3D Model ViewerOpen and inspect any GLB, GLTF, STL, OBJ or PLY model.GLB ViewerOpen and inspect .glb models in your browser.glTF ViewerView .gltf and .glb models in your browser.OBJ ViewerOpen and inspect .obj 3D models.PLY ViewerOpen .ply scans and meshes in your browser.

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How to use it

Open your STL

Turn and measure

Check size, screenshot