Licenses of third party libraries.

All used libraries have permissive open source licenses allowing use of their code in a closed-source software.

Third-party software in the repo

All third-party software are placed under /deps directory.

zlib - zlib license
lua - MIT license
libpng - libpng license (see /deps/libpng/LICENSE)
libsquish - MIT license (see /deps/libsquish/README)
GLEW - modified MIT license
eigen - Mozilla Public License 2.0 (LGPL parts of eigen are explicitly excluded by having "#define EIGEN_MPL2_ONLY" in /math/eigen.hpp)
sqlite - in public domain
bullet - zlib license
http-parser - MIT license
utf8 - MIT-like license (see /deps/utf8.h heading comment)
libogg - BSD-style license (see /deps/libogg/COPYING)
libvorbis - BSD-style license (see /deps/libvorbis/COPYING)
v8 - New BSD license (see /deps/v8/repo/LICENSE)
freetype - Freetype license (see /deps/freetype/repo/docs/FTL.TXT)
harfbuzz - "Old MIT" license (see /deps/harfbuzz/repo/COPYING)
lz4 - BSD license
npapi - Mozilla Public License 1.1
fcgi - BSD-style license (see /deps/fcgi/LICENSE.TERMS)
assimp - BSD license (see /deps/assimp/repo/LICENSE)
softfloat - BSD license (see /deps/softfloat/softfloat/COPYING.txt)
icu - Unicode license
discord-rpc - MIT license
rapidjson - MIT license
botan - BSD-2 license (see deps/botan/repo/license.txt)

These are not placed in the repository, but could be used by various parts of the engine: