# Licensing

Zulip is distributed under the [Apache 2.0
license](https://github.com/zulip/zulip/blob/main/LICENSE). This means that all
contributions to Zulip — code, images, sounds, etc. — must be compatible with
this license.

## Contributing your own work

If the work you are contributing is 100% your own, Zulip doesn't require you to
sign a copyright assignment or a contributor license agreement for your
contribution. As noted [in the GitHub Terms of
Service](https://docs.github.com/en/site-policy/github-terms/github-terms-of-service#6-contributions-under-repository-license):

> “Whenever you add Content to a repository containing notice of a license, you
> license that Content under the same terms, and you agree that you have the
> right to license that Content under those terms... This is widely accepted as
> the norm in the open-source community; ...”

## Contributing someone else's work

If any part of your contribution is from someone else (code snippets, images,
sounds, or any other copyrightable work, modified or unmodified), you need to
check whether it was distributed under an open-source license that is
[compatible][wiki-compatibility] with the [Apache 2.0
license](https://github.com/zulip/zulip/blob/main/LICENSE). If it was not, this
work cannot be contributed to Zulip, with or without modification.

[wiki-compatibility]: https://en.wikipedia.org/wiki/License_compatibility#Compatibility_of_FOSS_licenses

If you have verified that the work is OK to use, you will need to provide
appropriate attribution in the [`docs/THIRDPARTY`
file](https://github.com/zulip/zulip/blob/main/docs/THIRDPARTY) as part of your
PR. Please refer to the [`debian/copyright` file
documentation](https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/)
for a detailed description (including examples) of how to correctly describe the
copyright and licensing information in your PR.

If you are not sure about the licensing or attribution for your work, please
include the full details of your open questions in the description for your PR.
