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What do you need to get done?
- Stays on this device
- No watermark
- Works offline
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STL repair
Repair a broken STL so your slicer accepts it: merge loose corners, remove duplicate and empty triangles, turn flipped normals, fill small holes. You see what changed, before and after. Free, online, and the model stays in your browser.
How to repair an STL file
- 1Drop an STL, 3MF, OBJ or PLY file in
- 2Read the list of what was fixed, and switch Before and After
- 3Click "Save repaired STL"
- A repaired STL and a report of every change.
What happens to your model
- Your model is not uploaded.It is repaired in your browser, on your own device.
- Every fix is counted.Joined corners, removed triangles, turned faces and filled holes are listed.
- Compare before and after.A table and a 3D preview show open edges in red, before and after the repair.
What you can do
- Merge corners that lie closer than a distance you set (0.001 mm to start with), so edges line up.
- Remove triangles with no area and duplicate triangles.
- Turn triangles and whole inside-out parts so they all face outward.
- Fill holes up to a number of edges you choose (200 to start with) and run the repair again with new settings.
- Compare closed or open, open edges, triangle count and volume before and after, and save the result as an STL.
Good to know
- Holes bigger than your limit are left open and reported as too big to fill. Raise "Fill holes up to" and click "Repair again" to try.
- Edges shared by more than two triangles are counted but left as they are.
- The tool also checks the result as a solid. It can report "Closed, but some triangles cross each other" when the model overlaps itself.
- Repair does not remodel. A model with large missing areas can stay "not closed yet".
- Units are millimetres, which is what STL files use by convention.
Questions
How do I fix a non-manifold or broken STL?
Drop the file in. The tool welds corners, drops bad triangles, aligns the faces and fills small holes, then shows what it did. Save the repaired STL.
What does "Watertight" mean?
Every edge is shared by exactly two triangles and all faces point outward, so the model has a clear inside. Slicers need that.
Can it fill large holes?
Only up to the limit you set under "Fill holes up to". Larger holes are reported and left open.
Is my STL uploaded?
No. The repair runs in your browser and the file stays on your own device.