Is publishing in a "pure" Open Access journal the only way to do Open Access?

No.

Publishing in a Gold Open Access journal (pay-to-publish) is the Gold route to Open Access (Gold OA). Works published via the Gold route are immediately accessible and are generally protected by an open licence such as Creative Commons.

However, there are other ways to publish in open access: the Diamond route (Diamond OA), the Green route (Green OA), and the Hybrid route (Hybrid OA).

The Diamond route (Diamond OA) is a model in which neither readers nor authors pay fees. Publication costs are covered by institutions, universities, libraries, or public funding. This model aims to guarantee equitable open access, without financial barriers for researchers, while ensuring the immediate dissemination of publications.

The Green route refers to the parallel publication (or self-archiving) of a version of the manuscript in an institutional repository. Open repositories may be institutional, such as our own SERVAL/IRIS, or discipline-based. Publication is often delayed (embargo period) and is only permitted for the author accepted manuscript (AAM), also known as the post-print. This is the manuscript accepted for publication (after peer review) but before any typesetting by the publisher. There is no additional cost for researchers following this route.

The Hybrid route (Hybrid OA) concerns subscription journals that offer the possibility of making certain articles open access upon payment of publication fees. In this model, a single journal may contain both restricted-access and open-access articles. Although this option allows immediate access to the relevant articles, it is criticised for the risk of "double-dipping."

Below you can find a diagram showing the routes to Open Access.