Green, Gold, Diamond, Hybrid: Open Access Models Explained

Open access labels sound simple until a funder asks which route you used, and the same colour can mean a free journal, a paid one, or a copy you deposited yourself.

Explainer · 10 min read · Directive Publications Editorial Team

What the colours actually encode

People do not use open access colours consistently. Some say "gold" for any journal where every article is free to read; others reserve it for journals charging an article processing charge (APC). Rely on the label alone and you can pay for a route your funder will not accept, or miss a free one it would.

Ask three questions of any route instead. Where does the open copy live, on the journal's website or in a repository? Who pays, the author's side, readers through subscriptions, or neither? And the one the colours leave out: which version is open, under what licence? That third question usually decides whether a route meets a funder's policy.

If the distinction between an accepted manuscript and a version of record is hazy, our guide to preprints, accepted manuscripts and versions of record sets it out.

Gold open access: the whole journal is open

In a gold journal, every article is free to read on the journal's website as soon as it is published, usually under an open licence such as CC BY, which lets anyone share and adapt the work, even commercially, provided they credit the authors.

Many gold journals cover their costs with an APC, paid by the author, a grant or an institution. But gold does not automatically mean a fee: some fully open journals charge nothing.

Before you submit, find three things on the journal's own website: the charge for your article type, the waiver route, and the licence. The Directory of Open Access Journals (DOAJ) requires listed journals to state every fee an author may be charged, or to state plainly that there are none. A journal that hides its fees until after acceptance has told you something. Our guides to APC waivers and funding language and choosing a journal without getting scammed cover those checks in more depth.

Diamond open access: no fees on either side

cOAlition S, the group of research funders behind Plan S, describes diamond open access as a model in which journals and platforms charge no fees to either authors or readers, and calls these initiatives community-driven and academic-led. Costs are carried by the organisations behind the journal: a university, library, scholarly society or public funder.

Under the broad definition of gold, a diamond journal is a gold journal without an APC. The separate term marks out journals that are non-commercial and community- or academic-owned; it was introduced in a 2013 tripleC article by Fuchs and Sandoval to name non-profit open access free of charge on both sides. Three checks stop diamond from being a label you take on trust:

• No fee means no fee. Look for an explicit statement that there are no submission, processing or page charges. A journal waiving its APC for an introductory period is a gold journal with a temporary discount.
• No fee says nothing about review. Diamond describes how a journal is paid for, not how rigorously it reviews. Check the editorial board, review process and licence as you would for any journal.
• Know who is behind it. A no-fee journal depends on a host that keeps paying its costs. If the site names no host institution or society, ask before you submit.

Hybrid open access: one open article in a subscription journal

A hybrid journal is a subscription journal that lets you make an individual article open, usually by paying an APC. Your article becomes free to read under an open licence; the rest of the issue stays behind the paywall, so the journal earns subscriptions and per-article fees at once.

Hybrid is where funder policies differ most, including between funders you might expect to agree. The Plan S implementation guidance says cOAlition S funders will not financially support hybrid open access fees in subscription venues, and set 31 December 2024 as the end of their support for fees under transformative arrangements, the transitional deals that funded hybrid publishing.

Individual members apply that differently. UKRI, a cOAlition S member, still lets its open access block grant pay for hybrid journals covered by an approved transitional agreement its research organisation is party to, and expects to phase that out in 2028 to 2029. So coalition membership settles nothing either way: read your funder's current policy. These agreements are also institution-specific, so the same journal may be covered for one co-author and not another.

If a fee is payable and nobody else will cover it, check the cheaper route first: depositing your accepted manuscript on your funder's terms may comply at no cost. Plan S states that open access fees should be covered by funders or institutions, not by individual researchers. Paying a hybrid fee from your own or your department's pocket is the last option, not the first.

Green open access: a second copy in a repository

Green open access means publishing in a journal, usually a subscription journal, and depositing a copy in a repository: your institution's, or a subject repository such as PubMed Central. There is no APC. The copy you deposit is usually your author accepted manuscript, the final version after peer review but before the publisher's copyediting and typesetting.

The publisher sets the terms, and without an open licence the repository copy may be free to read but not to reuse. Nor is the repository always your choice: medical funders often name the one they accept, so an institutional deposit alone can leave you non-compliant. Three cases medical researchers meet often:

• NIH. The 2024 NIH Public Access Policy requires author accepted manuscripts to be submitted to PubMed Central and made publicly available without embargo on the official date of publication. The 2008 policy it replaces allowed an embargo of up to 12 months. NIH describes depositing the accepted manuscript as a free pathway to compliance.
• Wellcome and other Europe PMC funders. Wellcome requires the article to be in Europe PMC under CC BY at publication. Europe PMC and PubMed Central are PMC International partners that share content, so a PubMed Central deposit normally appears in Europe PMC too. The licence, not the repository, is the usual cause of non-compliance.
• Plan S. The repository route accepts either the accepted manuscript or the version of record, openly available immediately on publication. The default licence is CC BY; CC BY-SA and CC0 are also accepted, CC BY-ND only when explicitly requested and justified.

Some funders also ask you to include a rights retention statement in your submission so the accepted manuscript can be shared under an open licence. If yours does, use its exact wording.

To check a journal's green policy, search for it in Jisc's open policy finder, which sets out, for the submitted, accepted and published versions, each way an article can be made open, with any embargo, licence and fee. Confirm on the journal's own site, because policies change. Compare the embargo it allows against the maximum your funder permits: where the publisher's is longer, the green route closes for that journal, and that is much cheaper to learn before submission than after acceptance.

At acceptance, save your accepted manuscript as a separate, clearly named file. It is the version you will deposit, and easy to lose once proofs arrive.

Bronze: free to read is not the same as open

Bronze describes an article free to read on the publisher's website but carrying no clearly identifiable open licence. The label comes from a 2018 analysis of open access prevalence by Piwowar and colleagues, who found many bronze articles in their sample had been made free after an embargo, and noted it was unclear whether such access was permanent.

Bronze matters for two practical reasons. Readers have no stated right to reuse the article, by translating it or adapting a figure. And an article with no open licence will not meet a policy that requires one, such as Plan S.

If your article appears free on the publisher's site, find its licence line before calling it open access in a grant report. If there is none, make a compliant copy available through one of the routes above.

Choosing a route before you submit

Settle open access before the manuscript leaves your hands. For each journal on your shortlist:

1. Read your funder's policy. Note the required licence, maximum embargo, the version and repository it names, and whether it pays APCs or hybrid fees.
2. Identify the journal's model. Is every article open (gold or diamond), or is it a subscription journal with an open option (hybrid)?
3. If there is a fee, find out who pays. Check for a grant line, institutional fund, library agreement or waiver.
4. Check the green policy against the funder's terms. Set the journal's deposit terms side by side with your funder's. Any mismatch on version, repository, embargo or licence rules that route out.
5. Choose the route that complies at the lowest cost to you, and record it next to the manuscript files so your co-authors know the plan.

A worked example: you hold an NIH grant and the journal that best fits your paper is a subscription title with a hybrid option. You need not buy that option, because depositing your accepted manuscript in PubMed Central for release on the publication date already complies at no cost. If a cOAlition S funder also supported the work, check its licence terms too: its repository route expects immediate availability under CC BY or another licence it accepts.

Where the colours stop being useful

A hybrid article and a gold article can carry the same CC BY licence and satisfy the same policy: a funder refusing hybrid fees objects to the payment, not to the result. Bronze and green look identical to a reader who sees only a free PDF, yet only one has a licence and a deposit record behind it.

So when a research office or grant report asks which route you used, answer in terms that can be checked: the version that is open, where it sits, its licence, who paid. Record those four facts at acceptance; the colour then becomes a summary, not something you rely on. You can read how Directive Publications handles licensing, publication charges and fee waivers on its For Authors page, and submit your manuscript when you are ready.