Open access publishing

Open access to publications is the oldest strand of the open science movement and a requirement in nearly every open science policy: a publicly funded result should be readable without a paywall. This perspective explains how open access works, the routes and licences involved, and the policy and infrastructure layers that make it happen. It is the publication counterpart to Sharing your data, which covers datasets, and Reproducibility, which covers code and provenance. For the funder mandates that require open access in specific jurisdictions, see the geographic perspectives, especially France, United Kingdom, and Europe.

Routes to open access

Open access is usually described by colour, denoting where and how a work is made open.

• Green open access means depositing a version of the manuscript in an open repository, alongside or instead of journal publication. The journal may remain subscription-based. This is the route that institutional and subject repositories such as HAL, bioRxiv, and arXiv provide, and it is the cheapest and most widely available.
• Gold open access means the version of record is published openly on the journal’s own site, usually funded by an article-processing charge (APC) paid by the author or their institution.
• Diamond open access is gold access without an APC: the journal is open to both readers and authors, funded by institutions, libraries, or grants rather than per-article fees. Diamond journals carry no cost barrier on either side, which makes them the model most aligned with equitable open science, and they are a growing focus of European policy.

A related distinction is the manuscript version. The author accepted manuscript (AAM) is the peer-reviewed text before the publisher’s typesetting; the version of record (VoR) is the final published article. Green open access typically deposits the AAM, because publishers more often permit it, while gold and diamond make the VoR itself open.

Licensing

Open access is defined not only by free reading but by reuse rights, expressed through licensing. The Creative Commons licences are the standard, with CC BY (attribution only) the most permissive and the one most open science policies require, since it allows text mining, translation, and redistribution. Retaining copyright is what allows an author to apply such a licence. The Plan S Rights Retention Strategy is built on this: by asserting a CC BY licence on the manuscript at submission, an author keeps the right to deposit it openly even when publishing in a subscription journal, making green open access available regardless of the journal’s own policy.

The policy layer

Open access requirements are set by funders and institutions, increasingly in coordinated form.

• Plan S, launched by the cOAlition S funder coalition, is the most significant coordinated intervention, committing member funders to require immediate open access under an open licence, with no embargo. Its Journal Checker Tool lets a researcher confirm whether a given journal satisfies their funder’s requirements.
• Research-assessment reform is the necessary companion to these mandates. DORA argues that journal-level metrics such as the Impact Factor should not stand in for the quality of individual work, and CoARA operationalises that commitment across European institutions. Without assessment reform, prestige incentives pull researchers back toward closed high-impact journals, so the two agendas are deliberately linked.
• National and funder mandates implement these principles in each jurisdiction. In France, Ouvrir la Science mandates open access through HAL, and the ANR Open Science Policy, CNRS Open Science, and Inserm Open Science set the corresponding institutional requirements. At EU level the EC Open Science Policy makes immediate open access a Horizon Europe condition.

The infrastructure layer

Policy requires infrastructure to be actionable, and the same systems that serve open data also carry open publications.

• Repositories provide the green route. HAL is the French national open-access publication archive; the preprint servers bioRxiv, medRxiv, and arXiv provide immediate open dissemination before peer review; Zenodo accepts publications alongside any other output. These are the same repositories described for data deposit in Sharing your data.
• Journal vetting is provided by DOAJ, the community-curated index of legitimate open-access journals. It is the reference funders and the Journal Checker Tool rely on to distinguish compliant venues from predatory ones, and the DOAJ Seal marks journals meeting the highest open-access best practices.
• Discovery and aggregation is handled by OpenAIRE, which harvests metadata from repositories and DOAJ across Europe to monitor compliance and make open outputs findable, and by COAR, which aligns repository interoperability internationally.

Open access in neuroscience

Neuroscience publishing follows the general pattern, with preprints now routine: bioRxiv is the dominant venue for posting neuroscience manuscripts ahead of journal review, and the major neuroscience funders are cOAlition S members or maintain equivalent mandates. Persistent identifiers tie published articles to the underlying open data and code, so an open-access paper, its dataset in a repository such as OpenNeuro or DANDI Archive, and its analysis pipeline can all be linked through DataCite DOIs and ORCID author identifiers. Open access to the publication is therefore one layer of a fully open result, complementing the data-sharing and reproducibility practices covered in the companion perspectives.