Convert OBJ to 3MF (Free)

Drop a .obj file, click Export, download the .3mf. The modern replacement for STL: named parts, per-object color, and units that are actually in the file.

Also converts STL, GLB, PLY, USDZ, WRL, STEP from the same file.

Runs in your browser. No upload, no signup, nothing to install.

Also from Innerscene: Circadian Lab, a free lighting calculator for room illuminance, melanopic EML, and glare.

Your OBJ file is read and converted on your own machine. It is never uploaded.

How to convert OBJ to 3MF

1
Open your .obj file
Drag it onto the viewer above, or click "Open an OBJ File". Files up to 200 MB open directly; the parse runs in a worker so the page stays responsive.
2
Pick 3D Manufacturing Format in the Export menu
Click Export in the toolbar, then 3MF (.3mf).
3
Download
The .3mf is written in the browser and saved straight to your downloads folder. No queue, no email, no watermark.

What survives the conversion

A file conversion is a translation, and formats do not carry the same things. Here is exactly what moves from OBJ into 3MF, and what does not.

Geometry	Kept	Both formats store triangle meshes, so the shape transfers directly.
Colors and materials	Reduced	OBJ can hold material colors and 3MF holds one color per object, so materials are flattened to that.
Textures	Dropped	3MF does not carry texture images, so a textured model arrives in flat material colors.
Layers and structure	Reduced	3MF has named objects but no layers, so each layer becomes a named part instead.
Units and scale	Kept	3MF stores an explicit unit. OBJ does not, so the size is taken from how the viewer read the file. Check the scale once on import.
Lines and points	Dropped	3MF geometry is manifold mesh only, so line work and point clouds are skipped.

What the 3MF writer emits: An OPC package in millimeters, Z-up, with each mesh as its own named object carrying a basematerials color, placed by a build item.

The source: Wavefront OBJ (.obj)

Triangle and quad geometry, UVs and normals, with material colors from the companion .mtl file.

The target: 3D Manufacturing Format (.3mf)

The modern replacement for STL: named parts, per-object color, and units that are actually in the file.

Opens in: PrusaSlicer, Bambu Studio, Cura, Windows 3D Builder, Fusion 360.

Your file never leaves your computer

Both the OBJ parser and the 3MF writer are JavaScript and WebAssembly running in your own browser tab. There is no upload step, no server-side conversion queue, and no copy of your file anywhere but your machine. That matters for drawings under NDA, for client work, and for anything you would not email to a stranger.

Frequently asked questions

▶Is this OBJ to 3MF converter free?

Yes. No signup, no watermark, no per-file limit and no paid tier. Innerscene.

▶Is my OBJ file uploaded anywhere?

No. The file is read with the browser file API and converted in the same tab. Nothing is sent to a server unless you explicitly click Share, which is a separate, opt-in feature.

▶Will my colors and materials survive the 3MF export?

OBJ can hold material colors and 3MF holds one color per object, so materials are flattened to that.

▶Do layers and named parts carry into the 3MF file?

3MF has named objects but no layers, so each layer becomes a named part instead.

▶Will the 3MF open at the right size?

3MF stores an explicit unit. OBJ does not, so the size is taken from how the viewer read the file. Check the scale once on import.

▶How large an OBJ file can I convert?

Up to 200 MB, and the ceiling adapts to how much memory your device reports. The conversion runs on your own hardware, so a desktop with plenty of RAM will handle more than a phone.

▶Can I convert 3MF back to OBJ?

Yes, the other direction works too. Bear in mind that anything the first conversion dropped is not restored by converting back. 3MF → OBJ

▶Which browsers does it work in?

Chrome, Edge, Firefox and Safari, on Windows, macOS, Linux, iOS and Android. No plugin and no extension.