Cost	Provider	API Name	Uses	Docs
?	Scopus	Serial Title API		Link
Free	OCLC	(Various)	Various	Link
?	Scopus	Abstract Retrieval API
Paid	ISSNIC	ISSN Portal API	Check ISSN numbers against titles etc.	Link
Paid	SpringShare	(Various)		Link
Free	Crossref	Crossref		Link
Free	ArXiv			Link
?	JSTOR
?	Elsevier	(Various)
?	Web of Science
?	Springer?
?	LoC			Link
?	British Library?			Link
Free to members	Moodle (VLE)			Link
Free	Google Books			Link
Free	Wikimedia			Link
Free	Wikidata			Link
Free	Scholarly	Scholarly	Search Google Scholar	Link
Free	JISC	Discovery
Free to members	JISC	Catalogue
(Free to members?)	JISC	JUSP resource usage
?	JISC	Sherpa services/Open Policy Finder		Link
Free?	Unpaywall	Unpaywall database		Link
Free	Internet Archive	Various	Various	Link
Free	Semantic Scholar	Semantic Scholar API	Find and explore scientific publication data about authors, papers, citations, venues, and more.	Link
Free to members	Third Iron	Browzine and Libkey	Various	Link
Free	CORE	CORE API	Access OA research papers and associated metadata	Link
Free	HathiTrust	Various	Metadata, page images, and OCR for 17+ million digitized items in HathiTrust Digital Library	Link
Free	Europeana	Various	Images, newspapers, books, and audio-visual material from cultural institutions across Europe	Link
Free	National Library of Medicine (USA)	Various	Several text mining tools for accessing various NLM databases and biomedical literature	Link
Free	OECD	OECD Data sets API	Access their datasets - see the Data Library	Link
Free	PLOS (Public Library of Science)	Various	Access to article corpus and article metadata	Link
Free	PubMed Central	Various	Open access full-text scholarly articles that have been published in biomedical and life sciences journals	Link
Free	Text creation Partnership	Various	A corpus of more than 70,000 transcribed and encoded historical texts from Early English Books Online (published by ProQuest), Eighteenth Century Collections Online (published by Gale Cengage), Evans Early American Imprints (published by the Readex division of Newsbank)	Link