AFLR3 is an unstructured tetrahedral element mesh generation code. It uses the Advancing-Front/Local-Reconnection (AFLR) procedure to generate a tetrahedral volume mesh from an existing surface triangulation. In boundary-layer (BL) generation mode it also uses the Advancing-Normal Boundary-Layer (ANBL) procedure to generate a tetrahedral, pentahedral, and/or hexahedral BL mesh adjacent to BL generating surfaces. Primary input is a surface triangulation. The input mesh file contains the coordinates and connectivity for a fully connected surface triangulation. It is available as a stand-alone executable or a suite of libraries for AFLR3 integration within other systems.