Are my files uploaded to a server?

No. This conversion runs entirely inside your browser using your own device’s processing power. The file never leaves your computer or phone, which is why it also works when your connection drops.

Why did my model lose its colours?

STL cannot store colour at all — it is a list of triangles. Every STL from every program is like this. Keep your OBJ for the coloured version and use the STL for printing.

Is the STL binary or text?

Binary, which is about a fifth the size of the text form for the same shape and is read by every slicer. Nothing is lost by it being binary — the numbers are identical.

Convert OBJ to STL

Runs on your device · Your file never leaves your device.

An OBJ carries shape, colour and texture; a slicer wants none of that. Drop the OBJ and get back a binary STL — the geometry, watertight as it was, in the one format every 3D printer and every slicer on earth reads without argument.

The colours are not lost through any fault of the conversion: STL has no way to store them. It describes triangles and nothing more, which is exactly why it became the printing standard. If you need the colours later, keep the OBJ — this gives you a printable file beside it, not instead of it.

The conversion runs on your own machine, which for a 3D file is the whole point: a model is usually a client’s product, a scanned property or something not yet announced. Nothing is sent to a server, so there is nothing to delete afterwards and nothing to take anyone’s word for.

How to convert OBJ to STL

Drop the OBJ file — and its companion files if it has any.
Check that STL is selected.
Press Convert.
Download the STL file.

Supported formats and limits

Input: OBJ
Output: STL
Companion files: MTL and texture images are used when you add them
Keeps animation: No — the format cannot store it
Where it runs: In your browser; the model is never uploaded

Not for: Repairing non-manifold geometry or holes — this converts the shape as it is; it does not mend a model that was already unprintable.

Frequently asked questions

Are my files uploaded to a server?: No. This conversion runs entirely inside your browser using your own device’s processing power. The file never leaves your computer or phone, which is why it also works when your connection drops.
Why did my model lose its colours?: STL cannot store colour at all — it is a list of triangles. Every STL from every program is like this. Keep your OBJ for the coloured version and use the STL for printing.
Is the STL binary or text?: Binary, which is about a fifth the size of the text form for the same shape and is read by every slicer. Nothing is lost by it being binary — the numbers are identical.

More you can do with a OBJ file

OBJ to GLB

Other ways to get a STL

GLB to STL

Related tools

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