Online 3MF viewer

To view a 3MF file without a slicer, drop it on the viewer above. Every object on the build plate opens in 3D where the slicer placed it, with the size in millimetres, the triangle count and the volume. It runs in your browser, so nothing is uploaded.

What is inside a 3MF file

A 3MF is not a single mesh but a package. The 3MF core specification says a 3MF document must use a zip archive, and recommends keeping the model in the /3D/ folder, for example 3D/3dmodel.model. That file is XML:

• Vertices and triangles for each object.
• A unit: micron, millimetre, centimetre, inch, foot or metre, with millimetre as the default. This is why a 3MF never arrives at the wrong scale.
• Objects and build items: a document may hold many objects, and the build list says which ones are on the plate and where.
• Optional thumbnails as PNG or JPEG.

Slicer projects add much more. Bambu Lab lists the geometry of every object, all slicing parameters and modifiers, the arrangement on one or more plates, colour information, hand-placed supports and project files such as assembly guides. Bambu Studio also follows the 3MF Production extension, which stores the mesh data in separate files inside the package. PrusaSlicer saves all objects, settings and modifiers in its 3MF projects.

Opening 3MF on Windows and Mac

Sources: Microsoft's deprecated features notes, Bambu Lab's 3MF compatibility article, Apple's Preview format list and the Babylon.js Sandbox docs.

What this viewer shows

The viewer follows the same rules a slicer uses for geometry. It reads every model file in the package, follows components into separate files, applies each object's position and rotation, and converts the declared unit to millimetres. Only objects on the build plate are shown.

It does not show colours, painted supports, modifiers or print settings. Those stay in the file untouched, because the viewer only reads it.

Convert it after viewing

• Need an STL for another slicer, a CAM program or a print service? The 3MF to STL converter exports one merged STL or one per object.
• Need OBJ, GLB or PLY? The STL file converter reads 3MF and writes every common format.
• Have loose STLs you want as one project? The STL to 3MF converter bundles them into a 3MF with one object per file.

For STL, OBJ, PLY and GLB files, the STL viewer and OBJ viewer work the same way.