Open access explained — gold, green, diamond and hybrid
Open access means a research paper is free for anyone to read online, with no subscription or payment. Traditionally, readers or their libraries paid for journals. Open access moves the cost elsewhere, so that knowledge — often funded by the public — reaches everyone, including students and researchers in countries with small library budgets.
The main types of open access
| Type | Where it is free | Who usually pays |
|---|---|---|
| Gold | The final version, on the journal's website, immediately | The author or their funder pays an article processing charge (APC) |
| Diamond (or platinum) | The final version, on the journal's website | Nobody pays: a university, society or government runs the journal |
| Green | An accepted manuscript in a repository (for example a university archive or PubMed Central) | Nobody extra: the journal itself may be paywalled |
| Hybrid | Single papers in a subscription journal, made free | The author pays a fee for that paper |
| Bronze | Free to read on the publisher's site, but without a clear open licence | — |
What is an article processing charge (APC)?
Many gold open-access journals charge a fee when a paper is accepted. Fees vary widely, from a few hundred to several thousand US dollars. Many publishers offer waivers or discounts for authors from lower-income countries — always ask before you submit. Diamond journals charge nothing to either readers or authors.
Licences: what readers may do
Open-access papers usually carry a Creative Commons licence. The most common, CC BY, lets anyone read, share and reuse the work as long as they credit the authors.
How to publish openly without paying
- Choose a diamond journal in your field — the Directory of Open Access Journals lets you filter journals with no fees.
- Deposit your accepted manuscript in your university repository or a subject repository (green open access). Check the journal's policy first.
- Post a preprint on arXiv, bioRxiv, medRxiv or SSRN before or alongside submission. See What is a preprint?
How to find open-access papers
The free Unpaywall browser extension and the "Free full text" filter in PubMed find free legal copies quickly. More tips in How to find research papers for free.
Watch out for predatory journals
Some journals take APCs without proper peer review. Before paying any fee, read our checklist: How to spot a predatory journal.