Paint 3D, Blender, Adobe Substance 3D Painter, Sketchfab, Cinema 4D, ZBrush, meshmixer, Face Gen, Sculptris, Topogun, Sunny 3D, 3D-Coat, ShapeWorks, Deep Paint 3D, picoCAD, BodyPaint 3D, Archipelis 3D, Dilay, Zero Brush, CrackArt, PlastiSketch, Tattoo, Pointshop3D, Quixel Mixer, Clavicula, Future Paint 3d, ShapeShop, SculptGL, 123D Sculpt, Corona Renderer, Bforartists, GroBoto, Curvy 3D, MeshMolder, Meta 3D Modeller, Blacksmith3D-Paint, Quidam, LipService w/LBrush for Maya, PloppSL, Sharp Construct, CB Model Pro, Misfit Model 3D, 3Shaper, Blacksmith3D-Morph are some alternatives to Autodesk Mudbox.