MeshLab

MeshLab is an advanced 3D mesh processing software system that is oriented to the management and processing of unstructured large meshes and provides a set of tools for editing, cleaning, healing, inspecting, rendering, and converting these kinds of meshes.

Website: http://www.meshlab.net/

MeshMixer

Meshmixer is software for working with triangle meshes.

Website: http://www.meshmixer.com/

Simplify 3D

Professional 3D Printing Software.

https://www.simplify3d.com/