FreeCAD - An open-source parametric 3D modeler
Lychee Slicer - A POWERFUL AND VERSATILE SLICER FOR SLA RESIN 3D PRINTERS With Lychee, prepare your 3D models for 3D printing: define the best orientation, create supports automatically, or manually, preview before sending them to your 3D printer.
Cura - Cura aims to be a end solution for personal 3D printing with RepRap based machines.
Slic3r - STL-to-GCODE translator for RepRap printers Here comes Slic3r! Its features are: - speed
MatterControl - MatterControl is a free, open source app that lets you organize and manage your 3D prints.
Repetier - Software for controlling RepRap style 3D-printer like Mendel, Darwin or Prusa mendel.