MARXAN is a family of software designed to aid systematic reserve design on conservation planning. With the use of stochastic optimisation routines (Simulated Annealing) Marxan generates spatial reserve systems that achieve particular biodiversity representation goals with reasonable optimality. Over the years, Marxan has grown from its standard two zone application to consider more complex challenges like incorporating connectivity, probabilities and multiple zones. Along the way, Marxan's user community has also built plug-ins and interfaces to assist with planning projects.
Computationally, Marxan provides solutions to a conservation version of the 0-1 knapsack problem, where the objects of interest are potential reserve sites with given biological attributes. The simulated annealing algorithm attempts to minimise the total cost of the reserve system, while achieving a set of conservation goals (typically that a certain percentage of each geographical/biological feature is represented by the reserve system).