All open source code has conditions attached. The majority of code which I have written in my lifetime has been open source and therefore is usually available for you to build from, distribute, or derive new works. There are some stipulations however and in this post I would like to help you understand how you can take code I have written.

A brief aside I find that using LLM-based coding assistants is unethical and morally corrupt. These large language models were trained on open source code en masse, with their different licenses and copyrights. Large-language models are effectively laundering that code and re-selling it to other developers. Cursor can help you write Terraform because its models slurped up code from Anton Babenko (Putin khuylo!) and thousands of others. Copilot is able to help you vibe-code a new Django app because it copied Tim Graham’s and countless other contributors’ code without attribution.

Their outputs are a contemptible parallel construction of intellectual property theft.

All of my code for the Delta Lake project is licensed under the Apache License 2.0. This means if you want to copy this code you are welcome to, but you should include the license text in your project and include attribution.

I have observed some confusion around attribution.

DO:

  • Include the copyright line from the license file where you’re copying code from, e.g. Copyright (2020) QP Hou and a number of other contributors. All rights reserved. for delta-rs
  • or if you’re lifting a snippet of code rather than whole files/modules, add a comment block around the section of code with the above copyright and mention that it’s under the Apache License
  • and include the copyright notice in built binaries from this code. The redistribution clause of the Apache License applies to source and object forms.

Also consider letting the upstream folks know! Most people open source code to contribute to the general commons. Sending an email “hey thanks for X” goes a long way to making friends!

Don’t:

  • Just copy and paste the code you want, laundering copyrighted code like an LLM.
  • Include nothing more than a comment in the source code with a link to code on GitHub.
  • Pilfer code and then come back around and ask for credit for some derived work. I have lost count of the number of times “I made this” has happened.

Since the “Business-Source License” nonsense started happening with Hashicorp, Redis, MongoDB, and other open source presenting companies, I have taken to licensing more and more of my code as AGPL. That does complicate matters a bit more but generally whatever you make with the AGPL code has to also be made freely available.

I write free and open source code because I believe that produces the most positive benefit for our society. I hope you can build something cool with code that I wrote, but please follow the conditions of the license!