Preview a limited STL repair
Fix three things in an STL: unused vertices, zero-area triangles, and triangles wound against their neighbours. It does not fill holes, close gaps or make a model printable. You preview, apply and undo each change, and the export is read back and checked.
Preview a change before applying it. Your file stays in your browser.
Is this the repair you need?
| Your problem | What to do |
|---|---|
| A slicer says the model has holes or open edges | This tool will not fill them. Find the openings in the mesh checker first. Then use a mesh editor that lets you accept the patch, or export again from the CAD source. |
| A slicer reports non-manifold edges | Locate them in the mesh checker. Choosing which surface to keep is a modelling decision, so it is not done here. |
| Some faces look inside out, or the mesh checker reports inconsistent winding | Correct it here. The repair turns triangles that disagree with their neighbours to match the majority. It refuses an open mesh and a split that is exactly even, and a model that is inside out as a whole is not changed. |
| The part is the wrong size | Repair does not resize or convert units, so it cannot fix this. |
| The file is too large or too dense | This tool does not simplify a mesh. It removes only triangles that have no area. |
The three it will do
Unused vertices, which are listed but referenced by no triangle. Exactly degenerate triangles, meaning zero area rather than merely thin. And winding, but only where a triangle's correct orientation follows from its neighbours without a choice being made.
Each runs as a preview. Nothing changes until you apply it, the original stays open beside the result, and undo goes back as many steps as you took.
What it refuses, and why
No hole filling. No vertex welding by distance. No simplification. No guessing at which side is inside.
Every one of those needs a tolerance or an assumption, and the wrong value quietly produces a model that looks repaired and is not. A tool that fills a hole by bridging its boundary can just as easily bridge two holes that were meant to stay separate. If your mesh needs that kind of work, it needs a mesh editor where you can see and set the tolerance, not a checkbox here.
The export is checked
The STL you download is read back in and compared against what was in memory: triangle count, dimensions, coordinates and topology. A file that fails that comparison is not offered. Start at the mesh checker if you have not yet seen what is actually wrong.