Over two dozen tools have been contributed by HDF users and are distributed from NCSA's anonymous FTP server at
hdf.ncsa.uiuc.edu in the directory /pub/dist/HDF/contrib. These utilities are not supported by NCSA. An updated list of all of the user-contributed HDF utilities is available in the README file in that directory. Other users have developed and maintain tools that they distribute from their own web and FTP servers. The web page What Software Uses HDF? at
http://hdf.ncsa.uiuc.edu/tools.html contains links to all such tools of which the HDF team is aware.