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What are Overlay Journals and Why Should We Care?

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Table of Contents

Introduction

What are overlay journals?

Overlay journals are a disruptive concept that emerged from the academic publishing ecosystem in the last two decades. Born from the open-access revolution and nurtured by the preprint culture, overlay journals flip traditional publishing on its head. They don’t host articles; instead, they curate, review, and certify research that already exists in open repositories like arXiv, bioRxiv, HAL, or Zenodo. Essentially, they lay a “journal layer” on top of freely accessible content, hence the term “overlay.”

For a long time, the academic world was tethered to a model where journals controlled not just peer review but also access and visibility. Overlay journals sever this dependency. They propose a decentralized, open, and potentially far more cost-effective alternative. But as with any model that upends tradition, overlay journals come with their own set of challenges, critics, and misconceptions. Let’s explore what overlay journals are, how they function, why they matter, and where they might be headed.

The Core Concept of Overlay Journals

An overlay journal is, at its core, a peer-review and editorial mechanism built on top of pre-existing content housed in open repositories. Unlike traditional journals, they don’t host or own the content they review. Instead, they identify relevant articles, organize peer review, and upon acceptance, “publish” the articles by linking to the already deposited preprints.

This separation of content hosting and peer review is what gives overlay journals their distinctive architecture. Authors submit their preprints to a repository and then notify the overlay journal of their submission. After undergoing peer review, accepted papers are labeled or linked by the journal, which may add metadata, editorial commentary, or indexing tags, but not necessarily move the file to another location.

A Brief History of Overlay Journals

The roots of overlay publishing trace back to the early 2000s, but the idea only began gaining traction in the 2010s. The rise of preprint servers like arXiv, SSRN, and later bioRxiv created fertile ground for this publishing experiment. One of the earliest and most prominent examples is the Episciences platform, which launched in 2013 and supports a range of overlay journals in fields like mathematics and computer science.

Another pioneer was Discrete Analysis, launched by mathematician Tim Gowers, a Fields Medalist, in 2016. Frustrated by high publishing fees and sluggish peer review timelines, Gowers envisioned a system where quality and speed weren’t sacrificed at the altar of prestige. His journal operates entirely on the overlay model, leveraging arXiv as its content hub.

By the 2020s, more overlay journals began cropping up, with fields like physics, economics, and even parts of the life sciences experimenting with this approach. Initiatives like the Open Library of Humanities and Peer Community In (PCI) expanded the footprint further, illustrating the growing appeal of the overlay model.

The Workflow of an Overlay Journal

The workflow of overlay journals typically begins with an author uploading a manuscript to a preprint repository. Once publicly available, the manuscript is then submitted to an overlay journal. From there, the peer review process proceeds much like in traditional journals, with editors assigning reviewers and collecting reports.

If the paper is accepted, the overlay journal provides a publication certificate or endorsement, often with a DOI digital object identifier (DOI) that points to the original repository version. The journal may host an accompanying editorial or commentary, but it does not rehost the full article. This drastically reduces server costs and simplifies digital archiving responsibilities.

In most cases, the overlay journal also ensures that metadata such as keywords, abstracts, and author affiliations are properly linked, making the paper discoverable via scholarly indexes and search engines. In some platforms like Episciences, the overlay journal operates on its own subdomain with full editorial infrastructure, even while depending on external hosting for content.

Economic Efficiency and Cost Models

One of the most touted benefits of overlay journals is their low cost. Because they don’t host articles and often operate on volunteer labor or minimal stipends for editors, overlay journals can offer peer review and certification at a fraction of the cost of traditional publishers.

For instance, the annual cost of running Discrete Analysis is reportedly under $15,000, a paltry sum compared to the millions spent by subscription-based giants or even some open-access platforms with hefty article processing charges (APCs). Episciences claims that some of its journals operate on budgets of around €5,000–€10,000 annually.

Overlay journals challenge the assumption that high-quality publishing requires high budgets. Their lean operations suggest that much of what bloats traditional publishing—glossy layouts, aggressive marketing, legacy tech stacks—might be less essential than previously thought. Overlay models bring the conversation back to basics: Is the science sound, and has it been responsibly peer-reviewed?

The Role of Preprints and Open Repositories

Overlay journals are deeply symbiotic with preprint culture. Without repositories like arXiv or Zenodo, overlay journals couldn’t exist in their current form. These repositories provide the infrastructure for document storage, long-term access, and sometimes even citation metrics.

This reliance also shifts the perception of what counts as “published.” In the overlay model, submission to a repository constitutes the initial act of publication, with the overlay journal serving as the validator rather than the gatekeeper. This decouples visibility from certification, a radical departure from the legacy journal system.

The preprint-repository model also means that research can reach audiences quickly. Rather than waiting six months for a journal to release a paper, readers can access preprints immediately and see the overlay certification later. This speeds up dissemination without compromising rigor.

Advantages of Overlay Journals

Overlay journals offer several compelling advantages. First, they foster openness. By leveraging preprints, they ensure that articles are accessible from the outset. There’s no paywall drama, no embargo periods, no frustrating logins.

Second, overlay journals are incredibly cost-effective. Their minimal infrastructure and reliance on open-source tools reduce operational overhead, making them ideal for underfunded disciplines or institutions looking for publishing alternatives.

Third, they can be more agile than traditional journals. With fewer bureaucratic layers, editorial decisions may come faster. Since academics find many overlays, they often prioritize community needs over publisher profits.

Finally, overlay journals encourage innovation. Since they are not bound to legacy formats or systems, overlays can experiment with open peer review, post-publication commentary, or dynamic content updates.

Criticisms and Limitations

Despite their promise, overlay journals face several challenges. One concern is prestige. Academia still emphasizes brand-name journals for hiring, promotion, and grant funding. Overlay journals, being relatively new, often lack the impact factors and visibility that researchers covet.

What are overlay journals - Research

There is also a concern around sustainability. Many overlay journals rely on volunteer labor. While noble, this model raises questions about long-term viability. What happens if the founding editor moves on? Is there enough funding to ensure continuity?

Another issue is technical fragmentation. Authors must navigate separate systems for preprint deposition, overlay submission, and metadata linking. For non-tech-savvy researchers, this can feel like assembling IKEA furniture with no instructions.

Finally, some fields have been slower to embrace preprints. In disciplines like clinical medicine or humanities, where preprints are less accepted, the overlay model may struggle to gain traction.

Discoverability and Indexing

Visibility is a significant challenge for overlay journals. While the articles are accessible, they may not always be indexed by mainstream databases like Scopus or Web of Science. This hampers citation tracking and academic credit.

However, efforts are underway to bridge this gap. Services like DOAJ (Directory of Open Access Journals) have begun indexing some overlays, and Crossref provides DOI registration and metadata support. Projects like OpenAIRE are also working to standardize metadata exchange between repositories and overlays.

In the future, if indexing services recognize the overlay certification layer as a valid peer-reviewed step, overlays may begin to catch up in credibility metrics. For now, despite their potential, they often remain niche.

Examples of Overlay Journals

Several overlay journals are worth noting. Discrete Analysis (mathematics), Quantum (quantum science), and The Open Journal of Astrophysics are leading examples. These journals operate entirely as overlays and have demonstrated strong editorial integrity and growing readerships.

Peer Community In (PCI) is another fascinating model. Rather than a journal, PCI is a platform that allows scholars to organize communities that peer-review preprints in various fields. Once reviewed and recommended, the article gets a certificate and a citation, even if it isn’t published elsewhere. PCI Biology and PCI Ecology are two prominent examples.

Episciences supports several overlays in mathematics and computer science, acting as both infrastructure and platform. Its integration with arXiv makes it a powerful example of how overlays can be scaled.

The Future of Overlay Journals

The growth of overlay journals depends on several factors: the normalization of preprints, the development of better indexing, and cultural shifts in academia. As funding agencies like cOAlition S push for open access, and as researchers grow weary of high APCs, overlay models may look increasingly attractive.

AI and automation could also help overlays thrive. Imagine intelligent metadata linking, automatic reviewer suggestions, or even AI-assisted editorial triage. These tools could reduce labor and streamline operations, making overlays even more sustainable.

We may also see hybrid overlays that combine peer review with post-publication commentary or overlays built on multimedia and data layers. The model’s low cost and low friction make it fertile ground for experimentation.

Conclusion

Overlay journals represent a refreshing reimagining of scholarly publishing. By decoupling certification from hosting, they challenge the bloated economics and sluggish workflows of the traditional model. They’re lean, open, and nimble—three traits that academia desperately needs more of.

Yet, they’re not a panacea. Overlay journals must overcome issues of prestige, discoverability, and long-term support. They require a cultural shift just as much as a technical one. However, as the cracks in the traditional model widen, overlay journals might not be just a curious side project. They might be the blueprint for what comes next.

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