What is a .f3d file?

What an F3D actually is

Fusion does not normally use files. A design lives in Autodesk's cloud, in a project, with every save kept as a version. The F3D is what you get when you ask Fusion to export a design to disk: a single archive containing everything the cloud copy held. Solid and surface bodies from the ShapeManager kernel, the component tree, sketches, construction geometry, user parameters, materials and appearances, joints, and the timeline that records every operation in order.

That completeness is the point. Import an F3D back into Fusion and you get the design exactly as it was, editable, with the timeline intact. It is a backup and transfer format for Fusion users, and it was never intended as an exchange format for anything else.

Nothing else reads it

The archive layout is undocumented and Autodesk publishes no reader, so no other application imports F3D. FreeCAD, Blender, SolidWorks, Onshape and Rhino all decline the file. Autodesk Viewer, the free browser viewer, displays an uploaded F3D, which is the only way to look at one without Fusion installed.

This is a different situation from STEP, which any CAD system reads, and from a SolidWorks part, which several competitors import. An F3D sent to someone without Fusion is a file they cannot use.

F3D and F3Z

A design with external references, meaning an assembly whose components are separate designs in the project, exports as an .f3z. That is a zip archive holding one F3D per referenced design plus the top-level one. Fusion's upload command understands it; unzipping it by hand and importing the pieces separately loses the links between them.

Where these files come from

Hobbyist and small-business 3D printing and CNC work, overwhelmingly. Fusion's personal-use licence is free for non-commercial use, which has made it the CAD package of a large share of the maker community, and F3D is the format those designs are shared in on Printables, Thingiverse and the like when the author wants recipients to be able to edit rather than only print. It is also the format of the many Fusion tutorials that ship a starting file.

Getting geometry out

Fusion's export command, on the file menu, writes the neutral formats directly: STEP, IGES, SAT, SMT, STL, 3MF and OBJ. Right-clicking a single body or component in the browser exports just that piece, which is the usual way to get one part out of an assembly for printing.

If you do not have Fusion, installing it under the personal-use licence, opening the F3D and exporting STEP takes ten minutes and costs nothing. STEP is the export to ask a Fusion user for if you want the exact geometry, and STL or 3MF if you only want to print it. Fusion exports STEP AP214 with colours, so appearances survive the trip.

Fusion updates itself and there is only ever one current version, so version mismatches between F3D files are rare. An old archive opens in current Fusion.

How to open a .f3d file

Only Autodesk Fusion opens a .f3d. Fusion's personal-use licence is free for hobbyists, so that is not as narrow as it sounds, and Autodesk Viewer displays an uploaded F3D in a browser without a licence. This site cannot read the format.

Nothing else imports it. FreeCAD, Blender, SolidWorks and Onshape all decline, because the file is a Fusion design archive rather than a geometry format.

The way out is Fusion's export command, which writes STEP, IGES, SAT, STL, 3MF and OBJ. A file named .f3z is a zip of several F3D archives, used for assemblies with external references; open it with Fusion's upload rather than by unzipping it. Fusion opens older archives without complaint, and a newer Fusion is the only Fusion, since it updates itself.