GADGET is free software for cosmological N-body/SPH simulations written by Volker Springel at the Max Planck Institute for Astrophysics.
GADGET can therefore be used to address a wide array of astrophysically interesting problems, ranging from colliding and merging galaxies, to the formation of large-scale structure in the universe.
The first public version (GADGET-1, released in March 2000[4] was created as part of Volker's PhD project under the supervision of Simon White.
Later, the code was continuously improved during postdocs of Volker Springel at the Center for Astrophysics | Harvard & Smithsonian and the Max Planck Institute, in collaboration with Simon White and Lars Hernquist.
The second public version (GADGET-2, released in May 2005[5] contains most of these improvements, except for the numerous physics modules developed for the code that go beyond gravity and ordinary gas-dynamics.