DOAJ (Directory of Open Access Journals) https://doaj.org/
Best place to find free, peer-reviewed, open-access journals and articles across many subjects.
PubMed Central (PMC) https://pmc.ncbi.nlm.nih.gov/
Best for medicine, biology, and health sciences; a free full-text archive from the U.S. National Library of Medicine.
PubMed https://pubmed.ncbi.nlm.nih.gov/
Excellent for biomedical research. It is mainly a search database, but it often links to free full text in PMC or on publisher sites.
Europe PMC https://europepmc.org/
Strong for life sciences and biomedical research with lots of free content. Be aware it can also include preprints, so check article type if you need peer-reviewed only.
CORE https://core.ac.uk/
Good for finding free research papers across many disciplines by aggregating open-access content from repositories and journals.
Google Scholar https://scholar.google.com/
Great starting point for searching scholarly literature, but not everything it finds is peer reviewed, so students should verify the journal/source.
Unpaywall https://unpaywall.org/
Helpful when you find an article behind a paywall; it locates legal free versions from repositories and publishers.
OpenAlex https://openalex.org/
A free, open catalog of scholarly research that can help users discover papers and identify open-access availability.