Convert STL files to 3MF online free in your browser. Preserve real-world units, eliminate scale errors, and export 3MF, STL or OBJ for any slicer.
Drag your .stl file into OwlCAD in your browser, verify its dimensions, and click Export to save it as a 3MF file. No software installation, conversion credits, or account creation required.
Upgrade legacy STL files to the modern 3MF format with exact scale and smaller file sizes.
STL files store unitless vertex coordinates, which is where scaling bugs come from. 3MF embeds explicit millimetres so models load at the right size in every slicer.
3MF is a ZIP archive of compact XML, so a converted file is typically a fraction of the size of the equivalent ASCII STL.
Inspect wall thickness, hollow solid volumes, repair non-manifold triangles, and combine parts before generating your output 3MF.
Drop your STL onto the build plate, refine your model, and export print-ready 3MF free in your browser.
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.
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.
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.
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.
3MF packs the mesh alongside exact real-world units, materials, colour data, and print metadata into a smaller, compressed archive. Unlike unitless STL files that can load at the wrong scale, 3MF removes unit ambiguity in slicers like PrusaSlicer, Bambu Studio, and Cura.
Yes. Once imported into OwlCAD, you can scale to exact millimetres, combine with parametric shapes using booleans, hollow the part for resin printing, and fix non-watertight mesh errors before exporting.
Yes. Importing, editing, repairing, and exporting STL, 3MF, OBJ, GLB, and STEP files in OwlCAD is 100% free. AI generation is the optional Pro upgrade.