MAD-X is a project with a long history, aiming to be at the forefront of computational physics in the field of particle accelerator design and simulation. Its scripting language is de facto the standard to describe particle accelerators, simulate beam dynamics and optimize beam optics at CERN.
MAD-X is the successor of MAD-8 and was first released in June, 2002. It offers most of the MAD-8 functionalities, with some additions, corrections, and extensions. The most important of these extensions is the Polymorphic Tracking Code (PTC) of E. Forest (see documentation).
MAD-X is released for the Linux, Mac OS X and Windows platforms for 32 bit (on demand) and 64 bit architectures (see releases). The source code is written in C, C++, Fortan77 and Fortran90.
The users support is provided through the e-group mad-usr, or directly by emailing to mad support. For questions or bug report, you must provide a clear description and a self contained minimalistic example that exhibits the unexpected behavior with the last release (see support).
The project support and maintainance strategy is based on the MAD team and collaborators to debug and improve the legacy code (see contributors). This task can become pretty complicated when dealing with the legacy code, and finding effective correction can take a significant amount of time (see support).
The links above are the officially maintained MAD links, but the previous MAD-X website is still online.