In general, the runtime and its class libraries are licensed under the terms of the MIT license, and some third party code is licensed under the 3-clause BSD license. See the file "PATENTS.TXT" for Microsoft's patent grant on the Mono codebase. The Mono distribution does include a handful of pieces of code that are used during the build system and are covered under different licenses, those include: Build Time Code =============== This is code that is used at build time, or during the maintenance of Mono itself, and does not end up in the redistributable part of Mono: * gettext m4 source files used to probe features at build time: GPL * Benchmark Source Files Logic.cs and zipmark.cs are GPL source files. * mono/docs/HtmlAgilityPack MS-PL licensed * mcs/jay: 4-clause BSD licensed * mcs/nunit24: MS-PL * mcs/class/I18N/mklist.sh, tools/cvt.sh: GNU GPLv2 Runtime Code ============ The following code is linked with the final Mono runtime, the libmono embeddable runtime: * support/minizip: BSD license. * mono/utils/memcheck.h: BSD license, used on debug builds that use Valgrind. * mono/utils/freebsd-dwarf.h, freebsd-elf_common.h, freebsd-elf64.h freebsd-elf32.h: BSD license. * mono/utils/bsearch.c: BSD license. * mono/io-layer/wapi_glob.h, wapi_glob.c: BSD license Class Library code ================== These are class libraries that can be loaded by your process: * mcs/class/RabbitMQ.Client: dual licensed in Apache v2, and Mozilla Public License 1.1 * mcs/class/Compat.ICSharpCode.SharpZipLib and mcs/class/ICSharpCode.SharpZipLib are GPL with class-path exception. Originates with the SharpDevelop project. * mcs/class/System.Core/System/TimeZoneInfo.Android.cs This is a port of Apache 2.0-licensed Android code, and thus is licensed under the Apache 2.0 license http://www.apache.org/licenses/LICENSE-2.0 The Licenses ============ These are the licenses used in Mono, the files are located: MIT X11: text available in the file mcs/MIT.X11 MPL: text available in the file mcs/LICENSE.MPL InfoZip: text available in the file mcs/LICENSE.INFOZIP.BSD