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3DAI
Free · runs in your browser · files stay on your device

3D Model Repair

Drop a GLB, GLTF, OBJ, FBX or PLY model to see what is wrong with its mesh: holes, open and non-manifold edges, flipped faces, duplicate vertices, zero-area triangles and loose specks. Fix them in one click and download the model in the same format, with its textures and UVs kept. Nothing is uploaded.

Loading the 3D model repair tool...

How to repair a 3D model online

  1. 1

    Drop your model

    Drag a .glb, .gltf, .obj, .fbx or .ply onto the tool. For an OBJ, drop the .mtl and texture images with it so the colours come back too.

  2. 2

    Read the report

    Every mesh is checked in your browser. Holes show as red lines on the model and non-manifold edges as orange, with a count for each problem.

  3. 3

    Fix in one click

    Press Fix all, or choose which fixes to run: weld, remove zero-area triangles, fix flipped faces, fill holes, remove loose specks, recompute normals.

  4. 4

    Download it

    Compare before and after, then download the repaired model in the format you dropped (FBX comes back as GLB), ready for your game engine, viewer or AR.

What it checks and fixes

Every mesh in the file is checked on its own, and every fix keeps the UVs, colours, normals, skin weights and morph targets of the vertices it keeps. Printing an STL? STL Repair is made for that. To change the size of a print, use Scale STL.

Open edges and holesEdges used by only one triangle, grouped into holes. Small holes are filled with new triangles that take their UVs and material from the edge of the hole. Very large openings (an intentionally open surface, like a plane or a cloth) are left open.
Non-manifold edgesEdges shared by three or more triangles, such as two parts glued along one edge. They are counted and drawn in orange so you can see them; separating them needs a remesh.
Flipped facesTriangles wound the other way from their neighbours, so they look dark or see-through. They are turned to match, and closed parts are turned to face outward.
Duplicate verticesVertices at the same spot with the same UV, normal and colour. They are merged. Vertices that only share a position, like both sides of a UV seam or a hard edge, are kept apart, so textures do not smear.
Zero-area and repeated trianglesTriangles with two corners in the same place, or with no area, and exact copies of another triangle. They are removed. Back-to-back pairs (a two-sided leaf or card) are kept.
Loose specksTiny pieces floating free, away from the rest of the model: under 1 % of the mesh (you can change it) and small next to the model. Common in scans and AI-made models. They are removed. Small parts that sit on the model, like eyes, buttons or bolts, are kept.
NormalsMissing normals are added, and normals that point against their triangle are recomputed. You can also recompute all of them smooth or flat.
Broken valuesVertices with NaN or infinite coordinates, which make some apps fail to open the file. The triangles that use them are removed.

Model too broken? Regenerate it with AI

Some models are past saving: parts missing, surfaces tangled through each other. Make a clean, closed model from a photo instead, or give a repaired model new textures. The AI tools use credits; this repair tool does not.

Regenerate it with AI →Re-texture it

More free 3D tools

STL Repair3D Model ViewerFBX to GLBOBJ to GLBScale STLAI 3D Texturing

3D model repair FAQ

Drop the model file onto the tool at the top of this page. It checks every mesh and lists the problems, with holes drawn in red. Press Fix all, check the After view, then press Download. It is free, with no signup and no install.
GLB and GLTF (including Draco and meshopt compressed files), OBJ with its MTL and textures, FBX (2013 or newer), and PLY in ASCII or binary. You get the same format back, except FBX, which comes back as GLB because browsers cannot write FBX files.
Yes. Every vertex keeps its UVs, colours, normals, skin weights and morph targets, and vertices on a UV seam are never merged, so the texture stays where it was. Untouched triangles keep exactly the same UVs. New triangles that fill a hole take the UVs and material of the hole's edge. Animations in GLB and FBX files are kept.
No. The model is read, checked, repaired and written again in your browser, on your device. Nothing is sent anywhere, so it also works for files you cannot share.
An open edge belongs to only one triangle, so the surface has a gap there; a ring of open edges is a hole. A non-manifold edge is shared by three or more triangles, like pages meeting at a book's spine. Both can break 3D printing, booleans, baking and physics, and some engines and viewers show them as gaps or dark seams.
It does not untangle surfaces that pass through each other, rebuild missing parts, or remesh non-manifold edges; it shows them so you know they are there. For a model that is badly broken, it is often faster to make a new one from a photo with AI.
Use this page for GLB, OBJ, FBX and PLY models for games, AR, the web or rendering, when you want to keep textures and get the same format back. For an STL you want to 3D print, use STL Repair: it is made for printing and gives you a clean STL.
Up to 2 million triangles and 300 MB of files. Large models take longer and need more memory; on a phone, keep it under about half a million triangles. If a model is too big, reduce it in your 3D app first.

Blender, Unity, Unreal Engine and Godot are named only to describe compatibility; The3DAI is not affiliated with or endorsed by them.