- BioMed Central
- CORE
- Department of Energy Pages (DOE Pages)
- Dimensions
- Directory of Open Access Journals (DOAJ)
- EngrXiv Preprints (Engineering Archive)
- High Throughput Experimental Materials (HTEM)
- HighWire Press
- Hindawi Publishing
- Lens.org
- OpenAIRE
- Open Research Central
- Paperity
- PLOS
- Project Euclid Mathematics and Statistics Online
- PubMed Central
- PubSpace – NASA
- ScienceOpen
- Bookboon
- DOAB Directory of Open Access Books
- IntechOpen
- National Academies Press
- Project Gutenberg
- DART-Europe E-Theses Portal
- National ETD Portal – South African Theses and Dissertations
- OpenDissertations
- PQDT Open
- The Live Lingua Project
- Online Courses
- BASE – Bielefeld Academic Search Engine
- Google Scholar
- Get the Research
- Open Access Button
- R4R
- Unpaywall
