science-articles
Europe PMC
A life-sciences literature collection maintained by EMBL-EBI, spanning around 43 million publications along with open full-text content. A single keyless search interface returns both metadata and, where available, the full text of an article. Reach for it when you want biomedical papers and need the actual article text rather than just a citation.
Academic papers API
Why it’s useful & how it works
Excellent: search + open full text in one keyless API. Works both ways.
What’s inside
~43M+ publications.
API access
https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=...&format=json ; fullTextXML
Access
Programmatic API access (a key may be required — see the API tag).