(doc_license)=

# License

## 2-clause BSD license

Copyright (c) 1991-2025, UChicago Argonne, LLC and the PETSc Developers and Contributors
All rights reserved.

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.

This license DOES NOT apply to any software that may be obtained via
the --download-package option of the PETSc configuration. Each of those packages are
covered by their own licenses.

## Contributing License Agreement

Contributions are accepted via [GitLab](https://gitlab.com/petsc/petsc) merge requests.
If you are planning a large contribution, we encourage you to discuss the concept on the
<mailto:petsc-dev@mcs.anl.gov> {ref}`mailing list <doc_mail>` and interact with us frequently to
ensure that your effort is well-directed. See the developers {ref}`documentation
<ind_developers>` for further details.

PETSc is distributed under a 2-clause {ref}`BSD license <doc_license>` (see above). The
act of submitting a merge request (with or without an explicit Signed-off-by tag) will be
understood as an affirmation of the following:

> Developer's Certificate of Origin 1.1
>
> By making a contribution to this project, I certify that:
>
> 1. The contribution was created in whole or in part by me and I
>    have the right to submit it under the open source license
>    indicated in the file; or
> 2. The contribution is based upon previous work that, to the best
>    of my knowledge, is covered under an appropriate open source
>    license and I have the right under that license to submit that
>    work with modifications, whether created in whole or in part
>    by me, under the same open source license (unless I am
>    permitted to submit under a different license), as indicated
>    in the file; or
> 3. The contribution was provided directly to me by some other
>    person who certified (1), (2) or (3) and I have not modified
>    it.
> 4. I understand and agree that this project and the contribution
>    are public and that a record of the contribution (including all
>    personal information I submit with it, including my sign-off) is
>    maintained indefinitely and may be redistributed consistent with
>    this project or the open source license(s) involved.

______________________________________________________________________

## Legacy License

:::{important}
PETSc is now distributed under a 2-clause {ref}`BSD license <doc_license>`. This
section containing the (roughly compatible) legacy PETSc license exists for
**historical purposes only**.
:::

### Licensing Notification

Permission to use, reproduce, prepare derivative works, and to redistribute to others this
software, derivatives of this software, and future versions of this software as well as
its documentation is hereby granted, provided that this notice is retained thereon and on
all copies or modifications. This permission is perpetual, world-wide, and provided on a
royalty-free basis. UChicago Argonne, LLC and all other contributors make no
representations as to the suitability and operability of this software for any purpose. It
is provided "as is" without express or implied warranty.

Principal Software authors

- Mathematics and Computer Science Division
- Argonne National Laboratory,
- Argonne IL 60439
- Any questions or comments on the software may be directed to <mailto:petsc-maint@mcs.anl.gov>.

Portions of this software are copyright by UChicago Argonne, LLC. Argonne National
Laboratory with facilities in the state of Illinois, is owned by The United States
Government, and operated by UChicago Argonne, LLC under provision of a contract with the
Department of Energy.

This license DOES NOT apply to any software that may be obtained via
the --download-package option of the PETSc configuration. Each of those packages are
covered by their own copyrights and licenses.

### DISCLAIMER

PORTIONS OF THIS SOFTWARE WERE PREPARED AS AN ACCOUNT OF WORK SPONSORED BY AN AGENCY OF
THE UNITED STATES GOVERNMENT. NEITHER THE UNITED STATES GOVERNMENT NOR ANY AGENCY THEREOF,
NOR THE UNIVERSITY OF CHICAGO, NOR ANY OF THEIR EMPLOYEES OR OFFICERS, MAKES ANY WARRANTY,
EXPRESS OR IMPLIED, OR ASSUMES ANY LEGAL LIABILITY OR RESPONSIBILITY FOR THE ACCURACY,
COMPLETENESS, OR USEFULNESS OF ANY INFORMATION, APPARATUS, PRODUCT, OR PROCESS DISCLOSED,
OR REPRESENTS THAT ITS USE WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS. REFERENCE HEREIN TO
ANY SPECIFIC COMMERCIAL PRODUCT, PROCESS, OR SERVICE BY TRADE NAME, TRADEMARK,
MANUFACTURER, OR OTHERWISE, DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT,
RECOMMENDATION, OR FAVORING BY THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF. THE
VIEW AND OPINIONS OF AUTHORS EXPRESSED HEREIN DO NOT NECESSARILY STATE OR REFLECT THOSE OF
THE UNITED STATES GOVERNMENT OR ANY AGENCY THEREOF.
