Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines.
Dimensions is a linked research knowledge system that re-imagines discovery and access to research. Dimensions brings together grants, publications, citations, alternative metrics, clinical trials, patents and policy documents.
Access millions of publications and Connect, collaborate and discover scientific publications, jobs and conferences. All for free.
Academia.edu is a platform for academics to share research papers. Provides access to over 25 millions of publications and connect with 15+ million researchers for free and share your research papers!
DOAJ is a community-curated online directory that indexes and provides access to high quality, open access, peer-reviewed journals. By 2020, it has 11,599 searchable articles from 14,602 Journals from 133 Countries around the world.
It offers full-text access to open access research papers. The content are aggregated from repositories & journals.