Goxel is described as 'Use Goxel to create and edit voxel graphics (3D images formed of cubes) using a simple but very intuitive editor interface. It's an open-source editor built with '. There are more than 10 alternatives to Goxel for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and Steam. The best alternative is 3D-Coat. It's not free, so if you're looking for a free alternative, you could try MagicaVoxel or VoxelShop. Other great apps like Goxel are Voxel Builder (Free, Open Source), Acropora (Paid), Cubik Studio (Paid) and Qubicle Voxel Editor (Paid).
With VoxPie creating a 3d model is easier than drawing in MS Paint. Geared towards indie game devs, it lets you easily paint 3d models with a mouse like you paint physical action figures. Create 3d props from existing pixel art, height maps and 2d shapes!
With VoxelMaker you can create 3D models of your own design and then render them with realistic lighting and shadows. Voxel models are made from 3D cubes and create a stylized, "blocky" look - much like a 3D version of pixel art.