On Contributor License Agreement (CLA)

CLA exist for the benefit of corporations. They want to profit from our free labour, but not take legal risks of potential copyright misattributions. Of course, this means that this shifts the burden to the contributor. I am sorry but I am not going to sign a legal document, with all the risks attached with it, or pay a lawyer, on top of providing free contribution.

If you want my contributions, this should be enough:

• I am giving you my word that I have the right to distribute the change.
• My contributions are licensed under the same license as the target project at the time of the contribution.

That’s all. Thanks!

Here is a more lengthy version that explains the situation pretty well:

Don't sign a CLA

A large minority of open-source projects come with a CLA, or Contributor License Agreement, and require you to sign one before they'll merge your patch. These agreements typically ask you to go above and beyond the rights you afford the project by contributing under the license the software is distributed with.

drewdevault.com

Acceptable CLA

https://elinux.org/Developer_Certificate_Of_Origin seems reasonable

https://developercertificate.org/ is good