SoftwareTools

KiCad
http://kicad-pcb.org/

EAGLE
https://www.autodesk.de/products/eagle/overview

LTspice
http://www.linear.com/designtools/software/

Ultimaker Cura
https://ultimaker.com/en/products/ultimaker-cura-software

Slic3r
http://slic3r.org/

OpenSCAD
http://www.openscad.org/

FUSION 360
https://www.autodesk.de/products/fusion-360/overview

PePaKuRa
http://www.tamasoft.co.jp/pepakura-en/

Arduino IDE
https://www.arduino.cc/en/main/software

Processing
https://processing.org/

VisiCut
https://hci.rwth-aachen.de/visicut