Open Access

The psychology preprint server.

The open social-sciences preprint server.

The community preprint server for the geosciences.

CERN’s catch-all repository for any research output.

The flexible repository for figures, data, and outputs.

The curated repository for research data.

The free, open index of the mathematical literature.

The free digital library of astronomy and astrophysics.

Europe’s open-science graph — research linked to the funding behind it.

The world’s largest full-text open-access aggregator.