Free STL repair that never uploads your file

Most "online STL repair" sites upload your model to their servers — a problem if it's a commercial design, client work, or just something you'd rather keep private. Ferdelance runs the entire repair engine in your browser: your file never touches a server, and you can verify that with your network tab open.

Why it happens

STL files break in familiar ways: duplicate vertices from bad exports, zero-area triangles, flipped normals that turn the model inside-out, and holes from damaged downloads. All of it is fixable without rebuilding your mesh.

How to fix it (about 30 seconds)

1. Drop your .stl into the checker — free inspection, no account, works with binary and ASCII STL.
2. See every defect highlighted in 3D: red for non-manifold edges, amber for open boundaries.
3. Auto-Repair welds, caps, and aligns normals in seconds, then hands you a clean binary STL.

More fix guides

• How to fix non-manifold edges
• Your 3MF isn’t watertight — here’s the fix
• Fix holes and missing faces in your model
• Repair a 3MF without losing your AMS colors