No upload · No account · Runs in your browser
Drop a binary or ASCII STL into the panel below and it renders in 3D on your own screen. The file is read locally by the page and never sent to a server — there is no upload step, no account, and nothing to install. Orbit, zoom, and read its exact bounding box before you slice.
Local session · nothing leaves this tab
Drop an STL file here
Binary or ASCII. The file is parsed in this tab and rendered with WebGL — no upload, no account, no file stored.
No file size limit except your own hardware
Parsing locally...
Could not read that file.
File
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Format
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Triangles
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File size
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Bounding box
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STL stores coordinates but no units. The bounding box is shown as millimetres, which is what most slicers assume. If the numbers look exactly 25.4× too small, the model was probably authored in inches — open theScale Inspector to check it.
Drop the file onto the panel — or choose it from your disk
Binary and ASCII STL both work. A 20 mm demo cube is built in if you just want to see the controls.
Orbit, zoom, and inspect the mesh
Drag to rotate, scroll or pinch to zoom, shift-drag or right-drag to pan. Double-click resets the camera. Keyboard: arrow keys orbit, + and − zoom, 0 resets. Wireframe view makes individual triangles visible.
Read the real dimensions before you slice
The stats panel reports triangle count, format, file size, and the X × Y × Z bounding box. If the size is wrong, fix the scale before the print, not after.
Short answers about formats, units, privacy, and file size.
No. The file is read with the browser's local FileReader API, parsed in memory, and rendered with WebGL. There is no upload endpoint on this page. If you open your browser's Network tab and load a model, you will not see the STL bytes leave your machine.
Yes. The viewer checks the 84-byte binary header and the declared triangle count first, then falls back to ASCII vertex parsing. Both formats render the same way, and the stats panel tells you which one you opened.
STL files are unitless. Most slicers assume millimetres, so a model authored in inches arrives 25.4 times too small. Check the bounding box in the stats panel and use the STL Scale Inspector to convert a target height into an exact slicer percentage.
There is no artificial upload limit, because nothing is uploaded. The practical limit is your device's memory and GPU. Very large meshes may take a few seconds to parse and can be slower to orbit on older hardware.
The viewer logic runs locally and the file never needs a connection. After the first page load, the 3D preview and parsing continue to work offline. Web fonts or icon files that were not cached may fall back to system fonts while you are disconnected.
No. A viewer shows shape, not printability. Use the STL Printability Checker to test for open edges, non-manifold geometry, degenerate triangles, and inconsistent winding before you slice.
Help me build this properly
Does this actually solve your problem, or not?
I built this to answer one question: what percentage do I type into my slicer. But I don't know if that is where your workflow actually breaks. Tell me what is broken, missing, or just plain useless here. Honest answers, especially negative ones, are worth more to me than anything else you could do on this page.