SculptGL is a free sculpting tool using WebGL. It's a full featured web app that can run in modern browsers. You can also download SculptGL standalone application for Windows, Linux, and Mac, and access all functions from web version.
SculptGL standalone features sculpting tools including Brush, Inflate, Smooth, Twist, Drag, etc., PBR Vertex Painting (color, roughness, metalness), with alpha texture support for each tool. You can import and export OBJ, PLY, STL files, read vertex color, and optimize post and pre transform cache (tipsy algorithm).
SculptGL supports also multiresolution sculpting including Quad-tri Subdivison (catmull-clark/loop), Reversion (compute opposite of subdvision if possible), Navigating from low/high poly level subdiv will retain sculpting changes, and keep UVs (both reversion and subdivison).
Moreover, SculptGL offers voxel remeshing, uses SurfaceNets meshing algorithm (produces quad-only mesh), uniform remeshing (quads will have the same size), and can also create non-manifold vertex. In case of a non closed mesh, a naive holefilling algorithm is performed first.
Other features include option to detect UV, dynamic topology, triangles only, operates in real time, local subdivision (create new triangles), local decimation (deletes triangles), and support for Undo/Redo.