Free 3MF Editor — Edit & Convert 3MF Files Online

Edit 3MF files online, free. Resize to exact millimetres, combine and hollow it, repair the mesh and export 3MF, STL or OBJ. No install, no sign-up to start.

Edit 3MF files online, true to size.

Open a 3MF, resize it to exact millimetres, combine and hollow it, repair it for printing, and export 3MF, STL, OBJ or GLB, free, in your browser, with no install.

Free to use · Runs in your browser · Start without an account

A real editor for the modern print format

3MF keeps units and scale where STL doesn’t, and OwlCAD is built around true millimetres, so it’s a natural fit.

Open & convert 3MF

Drag a .3mf onto the build plate, or import an STL and export 3MF. OwlCAD reads and writes both, plus OBJ and GLB, with units detected on the way in. A multi-material 3MF keeps its per-object colours, object names, and part types, so a coloured print arrives coloured.

True-to-size editing

3MF carries real-world units, and OwlCAD works in true millimetres, so parts keep their intended size. Move, rotate, and scale to exact values.

Combine & cut

Boolean union, subtract, and intersect your 3MF against parametric shapes: merge parts, add tabs or cut holes, non-destructively.

Hollow & repair

Shell a model to a set wall thickness, add drainage holes, and run the print check to repair non-watertight geometry before your slicer sees it.

Three steps, in your browser

A slicer is built to prepare a 3MF for printing, not to redesign it. To change the model itself you need an editor, and this one runs in a browser tab with nothing to install.

1 · Open the 3MF

Drag the .3mf onto the build plate, or click to choose it. Units are read on the way in, so the model arrives at its real size in millimetres, and a multi-material file keeps its per-object colours and names.

2 · Make the change

Select a part and type exact values to resize, move or rotate it. Combine it with other shapes or cut holes with a boolean, shell it to a wall thickness, and run the print check to repair a mesh that isn’t watertight.

3 · Export for your slicer

Export back to 3MF to keep units and colours, or to STL, OBJ or GLB, then open the file in your slicer as usual.

What happens to your file

It opens on your device, it is saved to your workspace as you work, and it exports back out in the format your slicer wants.

No upload queue

Your browser reads and renders the model itself, so it appears as soon as you drop it in — you are never queued behind anyone else’s upload, and the file does not travel anywhere before you can see it.

Saved, not discarded

Most online viewers forget your file the moment you close the tab. OwlCAD keeps the model in your own workspace and syncs it as you work, so it is still there when you come back to this browser. Create a free account and it follows you to any device, and your projects dashboard lets you delete anything you no longer want.

Exports to a real file

When you are done, export STL, 3MF, OBJ, GLB or STEP — the format your slicer or your colleague actually needs, not a project file that only opens here.

Drop in a 3MF and start editing

No download, no account needed, and your work saves in the browser as you go.

Frequently asked questions

Is the OwlCAD 3MF editor free?

Yes. Open, edit, and export 3MF files free in your browser, with no install and no sign-up to start. Only AI generation is part of the paid Pro plan.

How do I edit a 3MF file online?

Drag a .3mf onto the build plate, then move, rotate, and scale to exact dimensions, combine it with parametric shapes using booleans, hollow it into a shell or repair the mesh, then export 3MF again.

Does 3MF keep the right size and scale?

Yes. 3MF carries real-world units, and OwlCAD works in true millimetres throughout, so a part keeps its intended size on import and on export, which is ideal for 3D printing.

Can I convert 3MF to STL, or STL to 3MF?

Yes. Import either and export the other (plus OBJ and GLB). 3MF is the more modern, slicer-friendly format; OwlCAD reads and writes both.

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