Browser-local viewer
STL viewer
Open an STL and look at it, on your own machine. As well as rendering the mesh this measures it: real dimensions, triangle and shell counts, and the edge problems that decide whether it will print. Every other STL viewer on the web asks you to upload first.
Drop your STL files here
STL, OBJ, PLY, GLB, glTF, 3MF, SVG and DXF. Nothing is uploaded: files are read and inspected inside this tab. Checking what this device can handle...
Queue
No files yet. Drop models above, or use the file picker.
Inspection
Add a model to see its dimensions, mesh health and estimated volume.
Output
Units
Size and placement
Repair and cleanup
These can change the shape, so they need a before-and-after review before export.
Convert or repair this file as well
What this STL viewer shows and what it does not
- An STL declares no unit, so dimensions are shown in millimetres on the conventional assumption that the file was authored that way. Assign a different unit and every figure updates.
- STL stores no colour, materials or texture coordinates, so the model renders in a flat shading of your choosing. Nothing is missing from the render that is present in the file.
- STL stores no smooth normals either. Faceted shading is a faithful picture of what the file contains; smooth shading is computed here for viewing and does not change the file.
- Vendor-specific per-facet colour extensions are not read, because they are not part of the STL format.
- Very large meshes are refused before memory is allocated rather than crashing the tab, with a tighter budget on phones and on Safari.
Troubleshooting
The model looks blocky or faceted
That is what an STL is: flat triangles with no smooth normals. Switch to smooth shading to see it rendered with computed normals; the file itself is unchanged.
The dimensions look wrong
STL records no unit, so millimetres are assumed. If the model was authored in inches or metres, assign that unit and the measurements will be right.
It says the mesh is not watertight
The inspection panel counts open edges, non-manifold edges and separate shells so you can see how bad it is. Safe repair welds duplicates, drops degenerate triangles and fixes winding, and will never fill a hole.
The file will not open
Both ASCII and binary STL are read, and the format is detected from the bytes rather than the extension. A file that still fails is usually truncated: check its size against the source.
Questions
Is my STL uploaded to view it?
No, and it could not be. There is no API route, no server action and no storage in this project, and the Content Security Policy blocks cross-origin connections outright. Load the page once and you can disconnect from the network entirely.
What can it tell me beyond how the model looks?
Bounding-box dimensions, triangle and vertex counts, separate shells, open and non-manifold edges, degenerate triangles, duplicate vertices, and an enclosed volume when the mesh is watertight enough for the figure to mean anything.
Can I fix or convert it from here?
Yes. Repair, scaling and conversion are all in the same workspace; this page just leads with looking rather than exporting.