The Character data Hanzi Writer uses is from the
Make Me A Hanzi
project, which extracted the data from fonts by
Arphic Technology, a Taiwanese font
forge that released their work under a permissive license in 1999. You can
redistribute and/or modify this data (in the
hanzi-writer-data
github repository) under the terms of the
Arphic Public License
as published by Arphic Technology Co., Ltd. A copy of this license can
also be found in
ARPHICPL.TXT
of the hanzi-writer-data repo.