All R source code and source file src/htmltidy.cpp are released under the GNU AGPL license. ---- As per https://github.com/htacg/tidy-html5/blob/master/README/LICENSE.md, libtidy source code is: Copyright (c) 1998-2016 World Wide Web Consortium (Massachusetts Institute of Technology, European Research Consortium for Informatics and Mathematics, Keio University). All Rights Reserved. Additional contributions (c) 2001-2016 University of Toronto, Terry Teague, @geoffmcl, HTACG, and others." The authors of the libtidy sources also used other source code that is licensed GPL-2. All licenses in the included source files have been left intact. As required by the libtidy copyright notice, the following files are noted as being modified for use in this package: - src/alloc.cpp - src/sprtf.cpp Both of those files have been marked as modified in the license copyright header. ------ XMLDisplay has the following license: Copyright (c) 2007 Lev Muchnik . All rights reserved. You may copy and modify this script as long as the above copyright notice, this condition and the following disclaimer is left intact. This software is provided by the author "AS IS" and no warranties are implied, including fitness for a particular purpose. In no event shall the author be liable for any damages arising in any way out of the use of this software, even if advised of the possibility of such damage. $Date: 2007-10-03 19:08:15 -0700 (Wed, 03 Oct 2007) ------ vkbeautify is MIT licensed