Open edges and holes
Finds boundary edges that prevent an STL surface from forming a closed solid.
TutorialProcessed on this device
Your STL stays here. It is processed in this browser—not uploaded, stored, tracked, or sent to an AI service.
Private STL repair
Fix broken STL files.
See exactly what changed.
Diagnose print-breaking geometry, repair STL files, and download a freshly checked copy — all without your model leaving the browser.
✓Original stays untouched✓No account or analytics✓Honest before / after checks
First time here? Follow the STL repair tutorial
Drop your 3D file here
or choose it from your computer
STL, OBJ, or 3MF · detected automatically.
Up to 500 MB and 5,000,000 triangles. Available device memory may limit repairs.
OBJ & 3MFExperimental
No format selection needed. Geometry only; materials, textures, and slicer settings are not preserved. Repaired downloads are STL. Memory and archive safety limits still apply.
Supported features and limitations →Browser-based STL repair
Understand the damage before you change the model.
Fix3DFile combines local mesh diagnostics, conservative repair, and optional solid reconstruction in one private workspace.
Non-manifold geometry
Flags edges and vertices shared in ways that can confuse slicers and repair tools.
Duplicate and broken faces
Detects repeated triangles, zero-area faces, and inconsistent surface winding.
Disconnected shells
Counts separate mesh regions so unexpected fragments are easier to spot.
Before-and-after changes
Shows the original and repaired geometry together and records each repair step.
Solid rebuild deviation
Measures how far a reconstructed surface moved from the source model.
- 1Choose an STL
Load an ASCII or binary STL. Processing begins locally in a dedicated browser worker.
- 2Diagnose and repair
Review open edges, non-manifold geometry, shells, and other defects before choosing a repair method.
- 3Inspect and download
Compare the result with the original, review the change record, and save a separate repaired copy.
STL repair FAQ
Questions before you repair.
Is my STL uploaded to a server?
No. Fix3DFile reads, analyzes, repairs, and exports the STL in your browser. The repair workspace does not intentionally upload or retain your model.
What STL problems can Fix3DFile repair?
Safe repair handles unambiguous defects such as duplicate faces, degenerate triangles, inconsistent winding, and simple planar holes. Solid rebuild can create a new closed surface when conservative repair is not enough.
Does a successful repair guarantee a safe print?
No. Geometry checks do not validate slicer settings, G-code, printer condition, material strength, dimensions, or suitability for structural or safety-critical use. Always inspect and test the result.
Which 3D file formats are supported?
Fix3DFile detects STL, OBJ, and 3MF automatically. All three formats have the same file caps: 500 MB and 5,000,000 generated triangles, subject to device memory. OBJ and 3MF support is experimental and geometry-only, with additional archive and complexity safety checks. Materials, textures, and slicer settings are not preserved. Repaired downloads are STL.
What is the difference between Safe repair and Solid rebuild?
Safe repair preserves the original surface and avoids guessing. Solid rebuild voxelizes the shape and reconstructs a new closed surface, which can seal severe damage but may alter small details or intentional openings.