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

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