The first version of Mesh:Tool is now online when you choose the 3.1 version of Grid:Apps.
Documentation can be found here.
The initial functionality is very basic. The repair function is from Kiri:Moto. It will seal clean holes in meshes and remove duplicate and invalid faces. More sophisticated editing is coming soon.
Import formats: STL, OBJ, 3MF
Export format: OBJ (STL and 3MF coming soon)