This is a category of articles relating to Medical software which can be freely used, copied, studied, modified, and redistributed by everyone that obtains a copy: "free software" or "open-source software". Typically, this means software which is distributed with a free software license, and whose source code is available to anyone who receives a copy of the software.
Free health software forms a tree, with a structure identical (when the same pages exist in both) to that of Category:Health software. See that category's page for an outline of the tree. Pages in the Free tree are linked to corresponding pages in the other tree.