Episciences.org is a diamond open-access publishing platform that uses the overlay-journal model: instead of hosting and typesetting submissions itself, it builds peer-reviewed journals (“epijournals”) on top of manuscripts already deposited in open preprint repositories. It is operated by the Centre pour la Communication Scientifique Directe (CCSD), a unit of the French national research agency CNRS, in partnership with Inria and INRAE. This guide explains how the platform works, who runs and funds it, what it costs authors and readers, and where it fits alongside other diamond open-access and overlay-journal initiatives.
What is episciences.org?
Episciences.org (usually shortened to “Episciences”) is infrastructure for running diamond open-access journals as an overlay on existing open repositories rather than as standalone publishing sites. A journal on Episciences does not receive a manuscript directly from an author in the way a traditional journal does; instead, the author first deposits (or already has deposited) a preprint in a recognized open repository, and the Episciences-hosted journal’s editorial board takes that deposited version through peer review, revision, and acceptance. The platform itself provides the submission tracking, editorial workflow tooling, DOI assignment, and the public-facing journal website; it does not act as a traditional publisher taking copyright transfer or charging fees.
As of the platform’s own reporting, Episciences hosts around 46 journals spanning roughly a dozen disciplinary categories and has published close to 8,000 articles since launch. Because journal counts and article totals change as new titles join or cease, treat any specific figure as a snapshot rather than a fixed number, and check the platform’s own journals listing for the current count.
How the overlay-journal model works
The mechanics of publishing through an Episciences-hosted journal follow a consistent sequence:
- Deposit. The author deposits a manuscript in an open repository the target journal accepts submissions from — most commonly arXiv, HAL (the French national open archive, also operated by CCSD), or Zenodo. This deposit is the version of record the journal will eventually evaluate and, if accepted, publish against.
- Submission to the journal. The author submits the repository entry to an Episciences-hosted journal in the relevant field, pointing the journal at the deposited preprint rather than uploading a fresh file to a separate publisher system.
- Editorial assignment and peer review. The journal’s editorial board (editors-in-chief and associate editors specific to that title) assigns reviewers and manages the review process. Review models vary by journal — some run single-anonymized review, others run more open models — but the process itself is comparable in rigor to a conventional journal’s review.
- Revision. As with any peer-reviewed journal, authors typically revise in response to reviewer and editor feedback, depositing updated versions in the same repository.
- Acceptance and overlay publication. Once accepted, Episciences assigns the article a DOI and publishes it on the journal’s Episciences page as the certified, peer-reviewed version — layered on top of, and linked back to, the repository deposit rather than replacing it.
The practical effect is that the underlying content lives in established, independently-run open infrastructure (arXiv, HAL, Zenodo), while Episciences and its journals supply the part a repository does not: editorial selection, peer review, and the certification that a version has been formally vetted and accepted.
Who operates and funds episciences.org
Episciences is operated by CCSD, the CNRS unit that also runs HAL, France’s national open-access repository. Institutional support comes from CNRS, Inria, and INRAE, alongside France’s Ministry of Higher Education and Research. The platform has received European Union project funding through OpenAIRE Nexus and participates in SCOSS, the Global Sustainability Coalition for Open Science Services, which coordinates pledged funding from libraries, consortia, and research institutions for open infrastructure that does not rely on author or reader fees. This funding structure — public-institution and infrastructure-consortium support rather than article processing charges or subscriptions — is the same underlying model that makes the platform’s diamond open-access status financially sustainable rather than just a stated policy.
Cost model: true diamond open access
Episciences-hosted journals charge no article processing charge (APC) to authors and no subscription or paywall to readers. Published articles are typically released under a CC BY 4.0 license, meaning they can be freely read, downloaded, and reused (with attribution) by anyone. This places Episciences squarely in the diamond open-access category, distinct from gold OA (author-side APCs), green OA (self-archiving alongside a paywalled version), and hybrid OA (a subscription journal offering a paid open option article-by-article). For a side-by-side comparison of how these routes differ on cost, licensing, and who pays, see CASRAI’s Gold vs Green vs Diamond vs Hybrid Open Access comparison.
Because neither the author nor the reader pays directly, Episciences journals also register as compliant with funder open-access mandates that specify immediate, fee-free open access as an acceptable route, such as the framework cOAlition S’s Plan S establishes. Episciences’ own materials reference alignment with Plan S and with the Principles of Open Scholarly Infrastructure (POSI), a framework describing how open scholarly infrastructure should be governed, funded, and kept from vendor lock-in.
Disciplines and journals hosted on episciences.org
Episciences’ journal roster is concentrated in mathematics and computer science — a legacy of its origins in the arXiv-adjacent overlay-journal tradition — but has broadened over time to cover other fields. Long-running, well-established titles hosted on the platform include Discrete Mathematics & Theoretical Computer Science (DMTCS) and Logical Methods in Computer Science (LMCS), both established overlay journals in theoretical computer science and mathematics predating some of Episciences’ own infrastructure and later migrated or aligned onto it. Beyond mathematics and informatics, the current roster spans social sciences and humanities, physics, earth sciences, environment, health sciences, mechanical engineering, and biomechanics, plus a small number of conference-proceedings titles. Journal composition changes over time as new editorial boards launch titles or existing journals cease; consult the platform’s own journals directory for the current, authoritative list rather than treating any static count as permanent.
Repository relationships: arXiv, HAL, and Zenodo
Episciences journals are configured, title by title, to accept submissions from specific repositories rather than any open repository generically. arXiv is the dominant source for the mathematics and computer-science journals, consistent with the platform’s roots in the broader arXiv overlay-journal movement (which also produced independent examples like the Journal of Machine Learning Research lineage and Discrete Analysis, not hosted on Episciences itself). HAL, CCSD’s own national open archive, is a natural fit given shared operators, and is commonly used by Episciences journals in the humanities, social sciences, and French-institution-heavy fields. Zenodo, CERN’s general-purpose open repository, extends the model to disciplines and outputs — including conference proceedings and datasets tied to a submission — that arXiv and HAL don’t cover as naturally. This repository-first design is also why Episciences is described as an infrastructure layer rather than a standalone publisher: the platform depends on, and reinforces the value of, independently-operated open repositories rather than competing with them for content.
Editorial governance and peer-review standards
Each Episciences-hosted journal is editorially independent: it has its own editor-in-chief and editorial board, sets its own scope, and runs its own review policy within the platform’s shared infrastructure. Episciences itself does not centrally dictate a single peer-review model across all titles — some journals run single-anonymized review, others more open models where reviewer reports or identities are disclosed. For background on how these review-model terms differ and why the terminology matters, see CASRAI’s guide to diamond open access and, for the review-model vocabulary itself, ANSI/NISO Z39.106-2023’s standard peer-review terminology. What Episciences does provide centrally is the submission-tracking system, DOI registration, long-term archiving commitments, and a shared technical standard that keeps every hosted journal’s publication metadata consistent and machine-readable for indexers.
How episciences.org compares to other diamond OA and overlay models
Episciences sits within a broader family of initiatives working to decouple peer review and editorial certification from the traditional subscription or APC-funded publisher. It is worth distinguishing it from adjacent models CASRAI covers elsewhere:
- Traditional diamond OA journals that host their own submissions directly (rather than overlaying a repository deposit) still fall under the general diamond open-access definition but don’t use the overlay mechanism — the journal, not a repository, is the primary place content lives.
- Peer-review-and-recommend models, such as Peer Community In, evaluate preprints and publish a citable review/recommendation rather than an overlay-published, journal-formatted article — a related but structurally distinct way of adding peer review on top of a preprint.
- Reviewed-preprint models, such as eLife’s, publish structured public reviews alongside a preprint without a traditional accept/reject gate; CASRAI covers the mechanics of that approach in its eLife Reviewed Preprints guide.
What distinguishes Episciences within this landscape is that it produces a conventional-looking, DOI-bearing, accept/reject journal article — the output research administrators, tenure committees, and citation databases are most used to evaluating — while keeping the underlying cost structure and repository dependency of an overlay model.
What this means for research administrators
A few practical points matter for anyone supporting researchers who publish through Episciences-hosted journals:
- Funder compliance. Because Episciences journals are immediate, fee-free, CC BY open access, publications there generally satisfy funder open-access mandates (including Plan S-aligned funder policies) without requiring an APC waiver or a separate green-OA deposit step — though the underlying repository deposit itself may still need to be tracked for institutional reporting.
- Repository deposit workflows still matter. Because the overlay model depends on a prior repository deposit, an institution’s repository-deposit guidance (self-archiving policy checks via tools like Open Policy Finder / Sherpa Romeo) remains relevant even for a journal that itself charges nothing — the deposit is the substrate the journal publishes on top of.
- Indexing and metadata. Episciences assigns DOIs and publishes structured metadata for accepted articles, which supports standard citation-database indexing; administrators verifying a researcher’s publication record should expect an Episciences-hosted article to carry its own DOI distinct from (though linked to) the original repository deposit’s identifier.
- Infrastructure context. Episciences is one part of a broader open-repository and open-infrastructure ecosystem that includes initiatives like COAR’s Next Generation Repositories work on interoperable repository standards — useful context when evaluating how well an institution’s own repository choices align with overlay-journal submission requirements.
Frequently asked questions
Is episciences.org a diamond open-access platform?
Yes. Episciences-hosted journals charge no article processing charge to authors and no subscription or access fee to readers, with articles typically published under a CC BY 4.0 license — the defining characteristics of diamond open access.
Does episciences.org host content itself, or just review it?
Both, in a specific sense: the underlying manuscript version lives in an external open repository (arXiv, HAL, or Zenodo), but Episciences publishes and hosts the accepted, peer-reviewed, DOI-bearing version on the journal’s own Episciences page, layered on top of the repository deposit rather than replacing it.
Who operates episciences.org?
The Centre pour la Communication Scientifique Directe (CCSD), a unit of France’s CNRS, operates Episciences, with institutional support from Inria, INRAE, and France’s Ministry of Higher Education and Research, plus project funding via OpenAIRE Nexus and pledged support through SCOSS.
What disciplines does episciences.org cover?
Its roots and largest concentration of journals are in mathematics and computer science, but the current roster also spans social sciences and humanities, physics, earth sciences, environmental science, health sciences, mechanical engineering, and biomechanics.
Do authors need to submit to a specific repository before publishing with an Episciences journal?
Yes — each Episciences-hosted journal specifies which repository or repositories it accepts submissions from (commonly arXiv, HAL, or Zenodo), and a repository deposit is a precondition for journal submission rather than an optional extra step.
Is an Episciences-published article citable the same way as a traditional journal article?
Yes. Accepted articles receive their own DOI and standard citation metadata through Episciences, independent of the DOI or identifier the repository deposit itself may carry.
This guide reflects publicly available information on episciences.org’s structure, funding, and journal roster as of publication; specific journal counts, disciplines, and funding partners may change as the platform grows — consult episciences.org directly for current figures.
