stl repair
Repair an STL online
Fix holes, flipped normals, duplicate faces, and loose vertices in an STL so it slices cleanly. Free, with a before and after report.
Good to know
Repair merges duplicate vertices, drops degenerate and repeated faces, makes the normals face out, and fills small holes. A badly broken scan may still need remeshing.
How it works
- 1Drop an STL (or 3MF, OBJ, PLY, GLB) in the box above.
- 2We weld duplicate vertices, drop broken faces, point the normals out, and fill holes.
- 3Check the before and after report, then download the repaired file.
What gets fixed
Open edges: each hole’s boundary is closed with a fan of triangles.
Flipped normals: faces are turned so the mesh has a clear inside and outside.
Duplicate and zero-area faces, and vertices nothing uses.
About STL
STL (Stereolithography). The default 3D printing format since 1987: a bare list of triangles. Every slicer reads it, but it has no units, no color, and no parts.
Units: None in the file. Slicers read the numbers as millimeters. Up axis: Z. Opens in Bambu Studio, PrusaSlicer, Cura, OrcaSlicer, and Blender.
Questions
- Is STL repair free?
- Yes. You get 3 runs a month without an account. Sign in with your email, free, and there is no limit.
- Is my file uploaded?
- No. The file is read and converted in your browser. It never reaches our servers.
- Why does my slicer say the STL is not manifold?
- Some edges touch one face instead of two, or three faces share an edge. Repair closes the holes; edges shared by three faces may need a remesh.
Related tools
All tools- Convert STL to OBJFree STL to OBJ converter. Runs in your browser, so the file never leaves your computer. Preview the model, then download the OBJ.
- Convert STL to GLBFree STL to GLB converter. Runs in your browser, so the file never leaves your computer. Preview the model, then download the GLB.
- Convert STL to 3MFFree STL to 3MF converter. Runs in your browser, so the file never leaves your computer. Preview the model, then download the 3MF.
- Convert STL to USDZFree STL to USDZ converter. Runs in your browser, so the file never leaves your computer. Preview the model, then download the USDZ.
- Convert STL to STEPFree STL to STEP converter. Runs in your browser, so the file never leaves your computer. Preview the model, then download the STEP.
- STL viewer onlineOpen STL files in your browser. Measure distances and holes, cut a section, check it is watertight, and see the print weight. No install, nothing uploaded.
- 3MF viewer onlineOpen 3MF files in your browser. Measure distances and holes, cut a section, check it is watertight, and see the print weight. No install, nothing uploaded.
- OBJ viewer onlineOpen OBJ files in your browser. Measure distances and holes, cut a section, check it is watertight, and see the print weight. No install, nothing uploaded.