[open source - multiplatform] A guide to a tree code algorithm implementation, used for astronomical N-body simulations.

Cloudy is an extensive, well-established, large-scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. The web page contains links to papers published with cloudy, the most recent version of the software itself, and a discussion board.

COSMOMC calculates a fast Markov Chain Monte-Carlo exploration of cosmological parameter space for an input set of constraints.

The Gadget-2 code is an SPH simulation code designed for cosmological simulations but can be used for a wide variety of astrophysical hydrodynamics simulations with self-gravity.

Grav-Sim is for astronomy and physics enthusiasts to conduct gravity simulations at home. It models a set of bodies gravitating under Newton's laws of motion.

ORSA is a C++ framework for the development of algorithms and programs oriented to the simulation and analysis of the orbital evolution of bodies in space.

A free computer program to calculate the strengths of atomic and molecular lines from interstellar clouds which are assumed to be homogeneous. Includes installation and running instructions and explains the output.

[open source - Windows] Various programs for stellar astrophysics. Includes CHANDRA stellar structure software for collapsed objects including rotating white dwarfs and neutron stars, and STARCAL for nuclear astrophysics and the stellar structure of main sequence stars with supernova forecasting.

[Open source - Linux] "Hubble in a bottle!" is visualization software for N-body simulations, which can be run in parallel using MPI for visualizing very large simulation results. Simulation output must be in TIPSY format.