Repair STL files online

Fix non-manifold edges, holes, flipped normals, and loose geometry in STL, OBJ, PLY, GLB, and 3MF files. Free, in your browser, no upload.

Repair the attached model: weld vertices, fix flipped normals, close holes

Files are processed entirely in your browser. Nothing is uploaded to a server.

Any 3D edit is just a prompt away.
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How to repair a 3D model online

Attach an STL, OBJ, PLY, GLB, or 3MF file above and press "Repair it". The tool welds duplicate vertices, re-orients flipped triangles, closes small holes, and optionally deletes loose debris shells. Those four defects cause most "non-manifold" slicer errors. Everything runs locally in your browser, so your model never leaves your computer.

When the badge turns green ("Watertight, ready to print"), the mesh is a closed solid that Cura, PrusaSlicer, Bambu Studio, and Orca will all accept without complaints.

Frequently asked questions

What does "non-manifold STL" mean?

A mesh is non-manifold when an edge is shared by more than two triangles, or when triangles are missing so the surface has open boundaries. Slicers can't tell inside from outside, which leads to failed or corrupted prints. This tool detects both problems and repairs the fixable ones automatically.

Can it fix every broken STL?

Small holes, flipped normals, duplicate vertices, and loose debris are fixed reliably. Heavily self-intersecting or fragmented meshes (raw 3D scans, for example) may need remeshing instead. If the result still isn't watertight, reduce the mesh first, or describe the part in GrandpaCAD chat and generate a clean replacement.

Is my file uploaded to a server?

No. The repair runs entirely in your browser using WebAssembly and JavaScript. Your model never leaves your machine, which also makes the tool fast for large files.

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