Here we list common licenses used by TeX-related software as recorded in The TeX Catalogue as maintained by Graham Williams. In all cases, please check the software's license before using the software. General information about categories of licenses is avaiable from GNU. License information recorded in the Catalogue can only be regarded as indicative. While I try to ensure it is accurate, and maintain it through input from authors, the sheer size of this task makes it difficult to maintain a watching brief on all licenses.
The license conditions are not designed to restrict what can be submitted to CTAN. Certainly, they are used to determine where the software will be located on CTAN (under the normal hierarchy or in the nonfree hierarchy with links from the normal hierarchy). In this way, redistributors of TeX and family can be surer (if not certain) of the legal situation. The simple criteria is that any software not satisfying the Debian Free Software Guidelines will be recognised as nonfree software.
Free software satisfies the criteria contained in the Debian Free Software Guidelines which provides the basis of the Open Source Free Software Guidelines. This software can be freely used, modified (hence source must be available), and distributed (e.g. on distributions like TeXLive, teTeX, and MikTeX). It is generally copyrighted to legally protect it. Users are generally given an explicit license to copy, distribute, and/or modify the software. Authors of free software may invite users to make monetary donations if they wish, but can not oblige them to do so, or else the software becomes nonfree. Free software may rely on nonfree software for extra functionality, but provides useful functionality without that nonfree software. Further information on free software is available from GNU.
While one category would be sufficient (dfsg) we identify the common subcategories that satisfy the DFSG:
| dfsg | Debian Free Software Guidelines | |
| artistic | Perl Artistic License | |
| bsd | BSD Style License | |
| fdl | GNU Free Documentation License | |
| gpl | GNU General Public License | |
| lgpl | GNU Library General Public License | |
| lppl | LaTeX Project Public License | |
| pd | Public Domain |
Nonfree software has restrictions on it that in some way prohibit its free distribution. Software in this category can not be included in distributions except, in general, with specific permission of the author or by payment of a fee. Because this software does not satisfy the Debian Free Software Guidelines, on CTAN it will be stored in the nonfree hierarchy (except for nosource which remains in the primary hierarchy) but will have links into the main hierarchy so that the casual user will still find it.
| unknown | Status is not known | |
| nocommercial | Free private use but commercial use not permitted | |
| nosell | Free use but distribution for profit by arrangement | |
| nosource | Freely distributable but no source code | |
| opl | Open Publication License | |
| shareware | Payment is requested if software is used | |
| other | General category for other non DFSG licenses |