Freetype
This is not legal advice. Read disclaimer.
Use of the Freetype-Go software is subject to your choice of exactly one of the following two licenses: * The FreeType License, which is similar to the original BSD license with an advertising clause, or * The GNU General Public License (GPL), version 2 or later. The text of these licenses are available in the licenses/ftl.txt and the licenses/gpl.txt files respectively. They are also available at http://freetype.sourceforge.net/license.html The Luxi fonts in the testdata directory are licensed separately. See the testdata/COPYING file for details.
Source: github.com/tdewolff/freetype@v0.0.0-20170521213346-62799869c6c6/LICENSE