· CORE – is a not-for-profit service, which aggregates all open access research outputs from repositories and journals worldwide and makes them available to the public.
· DOAJ (Directory of Open Access Journal) - is a community-curated online directory that indexes and provides access to high quality, open access, peer-reviewed journals. All DOAJ services are free of charge including being indexed in DOAJ. All data is freely available.
· DOAB (Directory of Open Access Books) - is a discovery service that points to Open Access books that can be found elsewhere. The directory is open to all publishers who publish academic, peer reviewed books in Open Access and should contain as many books as possible, provided that these publications are in Open Access and meet academic standards.
· OpenStax - is a nonprofit based at Rice University, publishes high-quality, peer-reviewed, openly licensed college textbooks that are absolutely free online.
· OPEN DOAR (Directory of Open Access Repositories) - is the quality-assured global directory of academic open access repositories.
· OATD (Open Access Theses and Dissertations) - the best possible resource for finding open access graduate theses and dissertations published around the world.
· ROAR (Registry of Open Access Repositories) - is to promote the development of open access by providing timely information about the growth and status of repositories throughout the world.
Domain repositories in the world
· OAD - is a compendium of simple factual lists about open access (OA) to science and scholarship, maintained by the OA community at large.
· Internet Archive - is a non-profit library of millions of free books, movies, software, music, websites, and more.
Digital library in the world
· EUROPEANA - is Europe’s digital library, museum, gallery and archive.