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3MF Package Inspector

Open a .3mf archive and see everything inside it: the OPC part graph, objects, build transforms, materials, declared extensions, thumbnails and the slicer settings hidden in it.

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Select a .3mf package

Accepted: .3mf

infoA 3MF is an OPC package — a ZIP with a content-type declaration, a relationship graph and at least one 3D model part. Everything in it is shown here, including the parts your slicer put there for itself.

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A .3mf is a ZIP with rules

Open a 3MF in an archiver and you get an OPC package: a [Content_Types].xml declaring what each part is, a relationship graph in _rels/.rels, and at least one 3D model part. That model part is conventionally 3D/3dmodel.model, but a conforming reader reaches it through the START_PART relationship, not by guessing the filename — and this inspector tells you which of the two happened for your file.

Slicers hang their own parts off the same package. A PrusaSlicer project carries Metadata/Slic3r_PE.config — its entire settings dump, several hundred keys of it — plus per-object configuration, layer ranges and a PNG thumbnail. That is why a project file is so much larger than the mesh inside it, and all of it is shown here in plain text.

What you get

  • Every ZIP entry with its size and declared content type, with the undeclared ones flagged. Real project files have several, and that is worth seeing.
  • The relationship graph, one table per .rels part, with each relationship's id, type and resolved target.
  • Model metadata — Title, Designer, Application, CreationDate and vendor entries such as slic3rpe:Version3mf.
  • Objects and build items, with the raw twelve-number transform and its decomposition. A negative determinant means the item is mirrored, which silently ruins threads, text and any chiral part while still looking correct on screen. That gets its own warning.
  • Materials and colours as swatches, colour groups and 2D textures.
  • Thumbnails, displayed and downloadable.
  • Declared units, and what one unit means in millimetres.

What it does not pretend to do

The Extensions panel lists every namespace the file declares with an honest support level. Core is read in full; Materials and Production are read in part; Slice data, beam lattices and encrypted packages are reported, not decoded; vendor namespaces are reported verbatim as unknown. Above eight million vertices the geometry preview is truncated while the counts stay complete.

Any part can be downloaded on its own, and the whole inspection exports as JSON. Everything runs in your browser — the file never leaves your machine.