- Dimensions
- Publish or Perish (Citation database)
- Lens.org
- dblp: computer science bibliography
- F1000Research
- PubMed Central (PMC)
- Social Science Research Network
- Indian Patent Advanced Search System
- Espacenet : European Patent
- LENS
- arXiv e-Print Archive
- CORE
- World Lecture Project World Bank Open data
- Directory of Open Access Journals
- PLOS
- Google Scholar
- Directory of Open access Books (DOAB)
- Project Muse
- Open Access books on JSTOR
- Open Library
- Internet Achieve
- Open DOAR
- Registry of Open Access Repositories