Blender, OpenScad , MeshLab (fait pour "nettoyer" les objets),etc...
===avec Blender===
{à traduire...}
Remove duplicate vertices
1. Hit Tab to enter Mesh Edit mode
2. Hit A to select all nodes (everything goes yellow and purple)
3. Type W6 or select Mesh -> Vertices -> Remove Doubles
Find non-manifold points
Non-manifold points are points that just don't make sense in the real world. These can be hanging points, internal surfaces, holes, zero-thickness walls, etc. Unfortunately there is no way to automatically fix them in software. The best you can do is to identify the problems and then attempt to fix them.
1. Hit Tab to enter Mesh Edit mode
2. Hit A to deselect all nodes (everything goes gray and pink)
3. Select Select -> Non-Manifold
If there are non-manifold points, they will be selected. If nothing happens, you're golden. If there are problems, then you can see what's wrong and attempt to fix it.