Not only paid labor, but also open source. As a developer I also enjoy it if I can help my customers more rapidly by using Open Source packages. With this in mind, I make packages as well.
Amongst others I work for
What is open source software?
The term "open source" refers to something - in this case, a chunk of code - that people can freely modify and share because its design is publicly accessible. So open source software is software with source code that anyone can inspect, modify, and improve.
The term originated in the context of software development to indicate a specific approach to making computer programs. Nowadays, however, "open source" refers to a broader set of values - what we refer to as "the open source approach". Open source projects, products or initiatives embrace and celebrate principles of open exchange, collaborative participation, rapid prototyping, transparency, meritocracy and community-centered development.