Are my STL files uploaded anywhere?

No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and watch that nothing is sent while the file converts.

Is converting STL to 3MF free?

Yes, without a limit on how many files you convert and with no watermark on the result. Files up to 100 MB are covered by the free plan.

Does converting STL to 3MF lose quality?

STL and 3MF describe content in fundamentally different ways, so the conversion is a reconstruction rather than a copy. The result is faithful, but not byte-for-byte equivalent. Geometry only. Materials, colours, textures and animation are not carried across, and a model placed several times comes back with each copy baked into its own position.

Do I need to install anything to open 3MF files?

No installation is needed for the conversion itself — it runs in the browser you already have. Opening the 3MF afterwards needs whatever software normally handles 3D Manufacturing Format on your device.

STLto3MF

Convert STL to 3MF

Up to 3 files at once, 100 with Pro. Mixed formats are fine.

You can convert STL to 3MF free and without an account: drop the file above and the 3MF is ready to download in a second or two. The conversion happens inside your own browser, so the file is never uploaded — it works on Windows, Mac, Linux, iPhone and Android, and keeps working with the network switched off.

What STL and 3MF are for

The 3D printing standard. Triangles only — no colour, no material, no texture.

The modern replacement for STL. Keeps colour, materials and units instead of bare triangles.

How to convert STL to 3MF

Drop your STL file onto this page, or click to pick one.
Choose 3MF as the target. The conversion runs inside your browser — the file is never uploaded.
Download the finished 3MF file.

STL vs 3MF: what changes

STL compared with 3MF
	STL	3MF
Full name	Stereolithography	3D Manufacturing Format
File extension	.stl	.3mf
Media type	model/stl	model/3mf

Quality: The result is a close reconstruction rather than an exact copy. Check it before relying on it.
Where it runs: This conversion runs inside your browser. Your file is never uploaded, and it works with the network disconnected.
What can be lost: Geometry only. Materials, colours, textures and animation are not carried across, and a model placed several times comes back with each copy baked into its own position.

STL to 3MF: common questions

Are my STL files uploaded anywhere?: No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and watch that nothing is sent while the file converts.
Is converting STL to 3MF free?: Yes, without a limit on how many files you convert and with no watermark on the result. Files up to 100 MB are covered by the free plan.
Does converting STL to 3MF lose quality?: STL and 3MF describe content in fundamentally different ways, so the conversion is a reconstruction rather than a copy. The result is faithful, but not byte-for-byte equivalent. Geometry only. Materials, colours, textures and animation are not carried across, and a model placed several times comes back with each copy baked into its own position.
Do I need to install anything to open 3MF files?: No installation is needed for the conversion itself — it runs in the browser you already have. Opening the 3MF afterwards needs whatever software normally handles 3D Manufacturing Format on your device.