Zulip is distributed under the Apache 2.0 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:

“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 with the Apache 2.0 license. If it was not, this work cannot be contributed to Zulip, with or without modification.

If you have verified that the work is OK to use, you will need to provide appropriate attribution in the docs/THIRDPARTY file as part of your PR. Please refer to the debian/copyright file documentation 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.