CORE
The world's largest aggregator of open-access research — full text at scale.
Tier 2 Open AccessFree
Research Database Directory
Every research database, reviewed.
BASE
Bielefeld Academic Search Engine — one of the largest indexes of the academic open web.
Tier 3 Open AccessFree
Crossref
The DOI backbone of scholarly publishing — metadata that ties the literature together.
Tier 2 ToolsFree
Mendeley
Elsevier's reference manager and academic network — capable, if you accept the ecosystem.
Tier 3 ToolsFree
Europe PMC
The open, full-text gateway to biomedical and life-sciences literature — PubMed's more open cousin.
Tier 1 Open AccessFree
OpenAlex
The fully open, CC0 index that set out to replace Scopus and Web of Science — bigger, free, and built for the Global South.
Tier 1 Open AccessFree
Google Scholar
The free front door to scholarship — vast, frictionless, and quietly imprecise.
Tier 2 AcademicFree
PubMed
The free, authoritative front end to the world's biomedical literature.
Tier 2 Open AccessFree
SSRN
The early-stage repository where economics, finance, and law circulate first.
Tier 2 CorporateFree
Zotero
The free, open-source reference manager most researchers already have — and underuse.
Tier 2 ToolsFree