# LAMMPS open-source license
## GPL version of LAMMPS
LAMMPS is an open-source code, available free-of-charge, and distributed
under the terms of the [GNU Public License Version
2](https://github.com/lammps/lammps/blob/develop/LICENSE)\_ (GPLv2),
which means you can use or modify the code however you wish for your own
purposes, but have to adhere to certain rules when redistributing it
-specifically in binary form - or are distributing software derived from
it or that includes parts of it.
LAMMPS comes with no warranty of any kind.
As each source file states in its header, it is a copyrighted code, and
thus not in the public domain. For more information about open-source
software and open-source distribution, see
[www.gnu.org](https://www.gnu.org)\_ or
[www.opensource.org](https://www.opensource.org)\_. The legal text of
the GPL as it applies to LAMMPS is in the LICENSE file included in the
LAMMPS distribution.
Here is a more specific summary of what the GPL means for LAMMPS users:
\(1\) Anyone is free to use, copy, modify, or extend LAMMPS in any way
they choose, including for commercial purposes.
\(2\) If you **distribute** a modified version of LAMMPS, it must remain
open-source, meaning you are required to distribute **all** of it under
the terms of the GPL. You should clearly annotate such a modified code
as a derivative version of LAMMPS.
\(3\) If you release any code that includes or uses LAMMPS source code,
then it must also be open-sourced, meaning you distribute it under the
terms of the GPL. You may write code that interfaces LAMMPS to a
differently licensed library. In that case the code that provides the
interface must be licensed GPL, but not necessarily that library unless
you are distributing binaries that require the library to run.
\(4\) If you give LAMMPS files to someone else, the GPL LICENSE file and
source file headers (including the copyright and GPL notices) should
remain part of the code.
## LGPL version of LAMMPS
We occasionally make stable LAMMPS releases available under the [GNU
Lesser Public License
v2.1](https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html)\_. This
is on request only and with non-LGPL compliant files removed. This
allows uses linking non-GPL compatible software with the (otherwise
unmodified) LAMMPS library or loading it dynamically at runtime. Any
**modifications** to the LAMMPS code however, even with the LGPL
licensed version, must still be made available under the same open
source terms as LAMMPS itself.