Analysing overlay journals: The state-of-the-art in 2021 and possible perspectives

The rising importance of preprints and the growing number of journals accepting them necessitate a (re)definition of an overlay journal and its place in today's publishing context. Using a snowball search strategy, we searched Web of Science and Scopus databases for articles on overlay journals. From these articles, we identified 28 overlay journals that fit the traditional overlay journal definition (they did not host articles but provided links to final versions on repositories or they searched repositories for viable preprints to publish) or that defined themselves as overlay journals. Most journals were not indexed in bibliographic databases, and crucial information such as journal ownership was not publicly available. Likewise, most journals both self-hosted articles and provided links to final versions on repositories, which might mean repositories are more valuable in their 'open access' functionality than in the capacity for hosting articles. Editorial policies and practices of these overlay journals were often undeveloped or non-existent. It seems overlay journals remain a niche publishing model in 2021, especially due to the increased number of journals accepting preprints and using preprint servers in their core functionality. However, overlay journals can take an 'active' approach in finding, reviewing, and publishing preprints, replacing other inefficient publishing models.