Many proteomics code repositories do not have a software license specified (Figure ). It is important to note that without a specified license the software is not open source. With an unspecified software license, the software and contributions are exclusively owned by the authors, and no one can use, copy, or distribute the contributions. The fact that so many proteomics tools have unspecified licenses underscores a misunderstanding of software licensing in the proteomics community. In addition, as the field is evolving and software becomes more complex and has multiple components, different components could have different licenses. Consequently, dependencies between these components should be clearly stated. We recommend clearly stating the dependencies that a piece of software might have and the licenses of each of them.