An economic perspective on software licenses—open source, maintainers and user-developers

This paper presents a model for understanding the behaviour of agents using and/or contributing to open source software. The model illustrates the behaviour of agents under three license regimes: (1) the GPL, (2) the BSD and (3) the Microsoft EULA. The latter license is not an open source license and is included as a reference as well as an example of a general situation where users do not contribute source code. The model uses economic theory of externalities and opportunity cost as a measure of agents’ costs. The basic premise is that agents will only participate in developments if there is a net benefit. Agents are divided into firms and individuals, which can be either maintainers or user-developers. A maintainer is an agent responsible for releasing new versions of a program and a user-developer is an agent who uses a program but may also become a developer. It is observed through the model that the three licenses induce different incentives and dynamics for maintainers and user-developers and the paper explains, from an economic standpoint, the mechanisms that ensure that programs are developed and maintained under the three license regimes.