Convert 3MF to STL online — free, no signup, no upload
3MF is a modern ZIP-based 3D-printing format; STL is the universal triangle-mesh format every slicer accepts. Converting 3MF→STL gives you a file that works everywhere, keeping the exact geometry. This converter runs entirely in your browser: your file is read on your device, converted, and downloaded — it is never uploaded to a server.
How to convert 3MF to STL
1. Drag your file onto the box above, or click Open 3MF file. 2. Preview the model in 3D to confirm it's the right one. 3. Click Convert to STL & download — the new file saves straight to your device.
Frequently asked questions
How do I convert 3MF to STL?
Drop your .3mf above (or click Open), preview the model, then click Convert to STL & download. It runs in your browser — nothing is uploaded.
Is the geometry preserved?
Yes — every triangle is carried over exactly; only the container format changes. STL doesn't store colour, so colour/material data in the 3MF is dropped.
Is my file uploaded?
No. The whole conversion happens on your device; your model never leaves your computer.