Fix a model, in your browser
- Drop a model — STL, OBJ, 3MF, GLB or PLY.
- It is repaired as it loads; the card says what was fixed.
- Save it as STL, 3MF, OBJ, PLY or GLB.
This free tool repairs 3D-printing meshes and converts between formats, in your browser. Drop an STL, OBJ, 3MF, GLB or PLY: it closes holes, turns flipped faces, removes duplicates, merges overlapping parts and checks that the result is a closed solid. What it fixed is listed, and the patches are shown in green. Save as STL, OBJ, 3MF, PLY or GLB.
New — 9 November 2026: first version, built on the repair engine of the mold maker. Written by Ned Walsch.
The same errors fixed in Bambu Studio and Blender too: How to fix an STL file.
| Problem | What you see in a slicer | Fix |
|---|---|---|
| Holes / open edges | "Non-manifold", missing walls, gaps in layers | Each boundary loop is traced and capped; flat loops by triangulating them, others with a fan |
| Flipped faces | Dark patches in the preview, wrong infill | Faces turned to agree with their neighbours; the whole shell turned outward |
| Duplicate faces / internal walls | Odd infill, "errors" warnings | Exact duplicates removed; back-to-back pairs (a wall inside the model) removed both |
| Overlapping parts | Extra walls inside the print | Merged into one outer surface with a real boolean union |
| Self-intersections | Slicer artefacts that repair cannot untangle | "Rebuild as one solid" |
| Format | Use it for |
|---|---|
| STL | Any slicer. No units, no colour — the universal choice. |
| 3MF | Bambu Studio, OrcaSlicer, PrusaSlicer, Cura: carries millimetres explicitly. |
| OBJ | Blender and other 3D apps. |
| PLY | Scanning and mesh tools (MeshLab, CloudCompare). |
| GLB | Web viewers, AR and game engines — written in metres with Y up, as glTF expects. |
Drop it on this page. It welds duplicate vertices, closes holes, turns flipped faces, removes duplicate and collapsed faces and merges overlapping parts, then checks the result with the Manifold geometry engine. If the mesh still is not a closed solid — usually because it intersects itself — it is rebuilt on a voxel grid. The mesh card lists exactly what was fixed.
Slicers need a closed surface with every face pointing out, so they can tell inside from outside. Downloaded and scanned models often have small holes, faces turned inside out, or several parts overlapping each other. Slicers patch some of this on the fly; repairing first gives you a file every slicer reads the same way.
It works out which points are inside the model on a fine 3D grid and builds a fresh surface around them, using exact distances to the original near the surface. Overlaps, self-intersections and small gaps disappear. Detail finer than the grid is softened, so use it when repair alone is not enough, and pick the fine grid for small detailed models.
Only where it was broken. Holes get flat or fan-shaped caps (shown in green), flipped faces are turned, duplicate faces removed, and overlapping parts merged into one outer surface. A model that was already a closed solid comes back unchanged. Rebuild and simplify do change the surface, and say by how much.
Drop the file here and pick STL under "Save as". It works the other way too: STL to 3MF, OBJ, PLY or GLB. 3MF and glTF carry units, so they come in at the right size; OBJ, PLY and STL have none, so check the size on the mesh card and change the units if it is off.
No. Reading, repairing, rebuilding and writing all happen in your browser with JavaScript and WebAssembly. The file never leaves your computer.