STL Repair Online
Fix mesh errors, close holes and preview your repaired STL.
Free · No account neededYour model
100 MB maxAdvanced settings
Files stay on your device · 200k triangles max
- Open your STL
Choose a file or try a sample.
- Choose your repair
Clean the surface or repair the solid.
- Preview & download
Check the actual output before saving.
A real repair, before and after
Curved opening · balanced reconstruction.
Rebuilding closes this opening as an indentation and changes the dimensions by 0.25%. Check thin walls and cavities.
More repair examples
Overlapping solids · two parts become one
Two 8,000-unit³ boxes with a 3,000-unit³ overlap. The outer dimensions are retained.
A simple planar hole
What repair changes
| Duplicate & collapsed triangles | Removed; before/after counts shown |
|---|---|
| Inconsistent winding | Reoriented across connected faces |
| Simple planar holes | Triangulated caps up to 128 boundary edges |
| Overlapping closed shells | Boolean union combines solid volumes and removes overlapping interiors |
| Complex openings & damaged surfaces | Grid reconstruction at coarse, balanced or fine detail; thin walls and cavities can change |
Original Quady3D AI examples · digital renders. Files and license.
Troubleshooting
Open edges remain after cleanup
Try Rebuild damaged surface for curved or branching openings. Compare the result: reconstruction can change the silhouette and fine details.
Non-manifold edges remain
Surface cleanup preserves ambiguous faces. Solid repair or reconstruction replaces the surface with a closed volume, with changes shown in the output report.
The report has no open edges
That alone does not establish printability. Cleanup does not detect every self-intersection or vertex-only contact. Reconstruction changes the volume; inspect thin walls and slicer-specific problems separately.
Questions
Can I repair STL files online for free?
Yes. This local tool removes duplicate and collapsed triangles, welds coincident vertices, fixes connected face winding and optionally caps simple planar holes. Advanced options also combine closed solids or reconstruct damaged surfaces using local WebAssembly. It provides a real binary STL download.
Can it fix STL holes and make every file watertight?
Not every input can be repaired faithfully. Grid reconstruction can close non-planar openings and replace intersecting surfaces, but thin walls, cavities and details can change or disappear. Review both previews, grid spacing, bounds change and sliced layers.
Will repair change the size?
Surface cleanup retains original coordinates. Boolean union and reconstruction change geometry; the report shows bounds change and grid spacing. STL does not declare a physical unit. Welding uses a tolerance of one ten-millionth of the longest side, with a small minimum. Added caps change geometry where an opening was filled. Import using your original units.