hover the model — it comes apart
or drop a file anywhere on the stage
STL · GLB · 3MF · OBJ
Free STL Viewer& Converter — no upload.
View, inspect and convert STL, GLB, 3MF and OBJ files right here in your browser — 100% private, nothing ever leaves your device.
↓ scroll for tools & guides
EVERYTHING RUNS ON YOUR DEVICE
One stage, every 3D file job.
Zero uploads
No endpoint exists. Go offline — everything still works.
How to view an STL file online
- Drop the file into the box above.
- Rotate with the left mouse button, pan with the right, zoom with the wheel — pinch and drag on a phone.
- Read the stats bar: triangles, vertices, meshes and the bounding box in the model's native units.
- Optionally export to STL, GLB or OBJ with the buttons below the preview.
Know the formats
Binary layouts, ZIP archives, what each format can and cannot store.
FAQ
Is my STL file uploaded to a server?+
No. The viewer parses your file with JavaScript in this tab using the three.js STL loader. There is no upload endpoint on this site. After the page has loaded you can go offline, drop a model, rotate it and export it — everything still works, which is the proof that nothing leaves your device.
Which file formats can this viewer open?+
STL (both binary and ASCII), GLB/GLTF, 3MF and OBJ. Drop any of them and you get the same 3D preview with triangle count, vertex count and bounding-box size. You can then export the model as STL, GLB or OBJ.
How big can the file be?+
There is no hard limit — parsing happens in your browser's memory, so the practical ceiling depends on your device. Models up to a few hundred MB open fine on a typical laptop. A very large mesh may take a few seconds to parse and render.
Why do I see triangle and vertex counts?+
Triangle count is the number slicers care about: it drives slicing time and file size. The bounding-box size tells you the model's dimensions in its native units (STL has no unit — most slicers assume millimeters). If a model imports at the wrong size in your slicer, the bounds shown here tell you whether it was modeled in mm, cm or inches.
Can I convert files here too, or only view them?+
Both. The viewer doubles as a converter: open a GLB, 3MF or OBJ and download it as STL for printing, or open an STL and export GLB for web/AR use. There are also dedicated pages per conversion — GLB to STL, 3MF to STL, OBJ to STL, STL to GLB and STL to OBJ — with notes specific to each format.
Does the viewer change my model?+
Viewing never modifies the file on disk. Exports re-encode the mesh: converting to STL keeps every triangle but drops colors, materials and textures, because the STL format cannot store them. Geometry is preserved exactly — no simplification, no remeshing.