musl as a whole is licensed under the GNU LGPL version 2.1 or later.
See the file COPYING for the text of this license.
See below for the copyright status on all code included in musl:
The TRE regular expression implementation (src/regex/reg* and
src/regex/tre*) is Copyright © 2001-2008 Ville Laurikari and licensed
under a 2-clause BSD license (license text in the source files). The
included version has been heavily modified by Rich Felker in 2012, in
the interests of size, simplicity, and namespace cleanliness.
Most of the math library code (src/math/* and src/complex/*) is
Copyright © 1993,2004 Sun Microsystems or
Copyright © 2003-2011 David Schultz or
Copyright © 2003-2009 Steven G. Kargl or
Copyright © 2003-2009 Bruce D. Evans or
Copyright © 2008 Stephen L. Moshier
and labelled as such. All have been licensed under extremely
permissive terms which are compatible with the GNU LGPL. See the
comments in the individual files for details.
The implementation of DES for crypt (src/misc/crypt.c) is Copyright ©
1994 David Burren. It is licensed under a BSD license compatible with
the GNU LGPL.
The smoothsort implementation (src/stdlib/qsort.c) is Copyright © 2011
Valentin Ochs and is licensed under an MIT-style license compatible
with the GNU LGPL.
The BSD PRNG implementation (src/prng/random.c) and XSI search API
(src/search/*.c) functions are Copyright © 2011 Szabolcs Nagy and
licensed under following terms: "Permission to use, copy, modify,
and/or distribute this code for any purpose with or without fee is
hereby granted. There is no warranty."
The x86_64 port was written by Nicholas J. Kain. See individual files
for their copyright status.
All files which have no copyright comments are original works
Copyright © 2005-2012 Rich Felker, the main author of this library.
The decision to exclude such comments is intentional, as it should be
possible to carry around the complete source code on tiny storage
media. All public header files (include/*) should be treated as Public
Domain as they intentionally contain no content which can be covered
by copyright. Some source modules may fall in this category as well.
If you believe that a file is so trivial that it should be in the
Public Domain, please contact me and, if I agree, I will explicitly
release it from copyright.
The following files are trivial, in my opinion not copyrightable in
the first place, and hereby explicitly released to the Public Domain:
All public headers: include/*
Startup files: crt/*