All the files in this distribution are covered under the MIT license (see the file LICENSE) except some files mentioned below:

src/string.c (memsearch_swar): 2 clause BSD license code by Wojciech Muła (@WojciechMula)
src/fmt_fp.c: public domain by Dave Hylands (@dhylands)
mrbgems/mruby-dir/src/Win/dirent.c: MIT-like license by Kevlin Henney

[src/string.c] The implementation of mrb_memsearch_ss() is taken from https://github.com/WojciechMula/sse4-strstr.git

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

[src/fmt_fp.c]

The code in this function was inspired from Fred Bayer's pdouble.c. Since pdouble.c was released as Public Domain, I'm releasing this code as public domain as well.

Dave Hylands

The original code can be found in https://github.com/dhylands/format-float

[mrbgems/mruby-dir/src/Win/dirent.c] used only for Windows platform

Permission to use, copy, modify, and distribute this software and its documentation for any purpose is hereby granted without fee, provided that this copyright and permissions notice appear in all copies and derivatives.

This software is supplied "as is" without express or implied warranty.

But that said, if there are any problems please get in touch.