I have been working with open source since 2016. I am an Apache Hadoop committer.
Open source code is available in general without any barriers. Whether you can use it depends on the specific license you are bound to. There are two kinds of open source licenses. Copyleft licenses like the one that controls the use of Linux, the most prevalent operating system these days have strong restrictions. These licenses grew out of academia. The original copyright belongs to the individuals, universities and companies, who wrote the code. Their original intention is to make it available to the users, who cannot afford the expensive commercial licenses and also to spark discussion. It also helps to market these products faster. If you intend to use these for commercial purposes, you either need to pay the original copyright holder or at least distribute your contributions under the same legal umbrella.
Copyright licenses on the other hand allow free usage and distribution with small restrictions. Some licenses for example even allow any users to use the software freely with any patents it uses. Patenting interestingly helps the project retain its free status in this case.
The difference becomes important with cloud services. Big cloud vendors like Amazon and Microsoft invest in hardware but sell services with open source software as a subscription. They insist that they can still use copyleft licensed software, since they do not redistribute the code but the service instead. Vendors and their customers argue that the restriction on open software limits opportunity as the license never expires as opposed to patents.
My opinion is that we see some shift in this area in this decade with so much AI generated code available.
The amount of software that accumulated in the past decades makes it impossible for anybody to review all of it and enforce all the licenses. Even with the help of AI the number of legal professionals available is limited. New software companies can almost freely write software without any legal risk that would limit their opportunity. There are simply so many open source examples to cite. Trivial patterns usually appear in many places, and model vendors already use this to identify publicly available training material. When the contributor creates code without knowledge of previous work, it is less risky than before. A common pattern called reverse engineering, when one developer analyzes code and another creates a new one with a different license based on the same requirements. Copyright usually protects the exact word order, not the physics or logic behind it.
Every software contains clauses about limited warranty. This made sense decades ago, when there were fewer professionals compared to lawyers. Authors had to protect themselves against misuse. Nowadays there are millions of software professionals. Software is reusable, there is no way to provide a legal response to every single bug. The result is the rise of services like GitHub, where anybody can write sketches of code without any fear of misuse. This is important. Any work you distribute under an open source license states its purpose implied. The fact that it is free to use suggests that not many resources were spent to test it. An open source developer still has responsibility. They need to make sure not to commit any issues intentionally. They must not inject security back doors into the code. The responsibility is split then with the cloud vendors and service providers, who should review every single line of code used and run extensive testing. AI helps in 2026. Integrity is the responsibility of the original copyright owner. Patent compliance, reliability and security are the responsibility of the providers to the end users. This provides the value of commercial businesses that distribute free open source code.
Engineers and corporate legal departments give special care to licenses because all of them have a caveat. The BSD and MIT licenses do not grant access to any patents of the copyright holder. A malicious developer can inject legal liability into an ecosystem. Apache licenses take a stronger ownership by requiring the copyright holders to license to the Apache Software Foundation instead of the end user. This applies to patents as well. The community has stronger ownership this way but it poses some legal risks for both the copyright owner and the end users, since the foundation is self governed. The risk increases, if special interests start supporting and lobbying a software foundation.
I share the opinion of the Free Software Foundation by suggesting to use the simple CC0 Creative Commons License. It supports creativity compared to community. This does not retain any rights to the copyright owner other than the basics like trademark and patents. This makes intellectual property easy to maintain. If you spent on patents or trademarks, those are yours. Any serious open source contributors do not patent software ideas. Any idea publicly distributed under this license cannot be patented anyway. This structure removes the legal risk from the system and provides the best tools for service providers and cloud vendors to add value to end users. This value includes legal responsibility, security, reliability, compliance that is represented by their own brands. Moreover patents and trademarks define the clear legal boundaries of platforms instead of patterns of obscure, hard to defend C Unix APIs.
Every human being is equal, so they should have the opportunity to come up with the same ideas freely based on empirical evidence. This means that any work that is derived using science is essentially free, too. The way you can imagine it is as a mineral that you mine. You get the rights to think freely by your constitution thus you can mine the mineral. Its value to you is given by the amount of work and resources you spent to come up with an idea or code. You cannot restrict others to come up with the same idea independently like you cannot restrict others to mine the same type of mineral in another region. This is why patenting is needed to protect the first inventor encouraging innovation. On the other hand, customers pay for the value that the software provides. The price of the hammer created from the mineral is not determined by the material itself. It is determined by the work that was required make it, and the value of product it makes possible.