Diamond Open Access refers to a scholarly publication model in which journals and platforms do not charge fees to either authors or readers.
Diamond Open Access journals are community-driven, academic-led, and academic-owned publishing initiatives, serving a fine-grained variety of generally small-scale, multilingual, and multicultural scholarly communities. These journals and platforms embody the concept of bibliodiversity.
For all these reasons, Diamond Open Access journals and platforms are equitable by nature and design.
For more information on Diamond Open Access visit Diamond Open Access | Plan S (coalition-s.org).
You can find Diamond Open Access Journals on the Directory of Open Access Journals (DOAJ).
The list on the DOAJ includes open access journals you would be required to pay an APC to publish in as well as free Diamond Journals. The easiest way to see just the Diamond Journals is to click on 'Journals Without Fees' as you can see highlighted below. From here you can filter down through country, language, subject etc.