GitHub's CLA gives project maintainers assurances about where contributions are coming from and what rights are being granted along with them.
Open source licenses serve as implicit contributor agreements. A formal CLA makes contribution terms explicit and provides the project maintainers a record of your agreement to those terms.
Most GitHub open source projects are released under the MIT license, which grants permission to use but does not expressly reference copyright or patent. The GitHub CLA expressly secures copyright and patent grants from you.
When making your first pull request to a GitHub maintained project, we want you to fully understand the permissions you are granting and make sure you have the rights needed to do so.
A wide range of terms exist in various other CLAs, including choice of law provision, waiver of moral rights, consequential damages waiver, as-is disclaimer, etc. The GitHub CLA does not contain any of these.
However, the GitHub CLA is not that different from the widely used Apache Individual Contributor Agreement. The GitHub CLA is more bare-boned, keeping the three clauses that are most important for ensuring contributions do not put the project or its maintainers at legal risk: copyright, patent, and source of contribution.
Additionally, the GitHub CLA is presented with user experience in mind. It’s short, comes with a two point summary and this FAQ, and can be signed with one click when making a pull request.
The service at cla.github.com is only available for projects maintained by GitHub. CLA assistant is a similar service available for any project hosted on github.com.