1991    An online repository of electronic preprints, known as e-prints, of scientific papers is founded in Los Alamos by the American physicist Paul Ginsparg. It was renamed to ArXiv.org in 1999. The total number of submissions by April 21, 2021 is 1,866,209 ( arxiv.org/stats/monthly_submissions).

1993    Creation of the Open Society Institute (renamed the Open Society Foundation [OSF] since 2001) by the progressive liberal business magnate George Soros. The OSF financially supports civil society groups around the world, with a stated aim of advancing justice, education, public health and independent media.

1997    Launch of SciELO in Brazil. There are currently 14 countries in the SciELO network and its journal collections: Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Mexico, Peru, Portugal, South Africa, Spain, Uruguay, and Venezuela.

1998    Public Knowledge Project (PKP) is founded by John Willinsky in the Faculty of Education at UBC dedicated to improving the scholarly and public quality of research. PKP has created the Open Conference Systems (2000), Open Journal Systems (2001), Open Harvester Systems (2002) and the Open Monograph Press (2013).

2000    BioMed Central, the self-described first and largest OA science publisher and PubMed Central, a free digital repository for biomedical and life sciences journal, is founded.

2001    An online petition calling for all scientists to pledge that from September 2001 they would discontinue submission of papers to journals which did not make the full-text of their papers available to all, free and unfettered, either immediately or after a delay of several months is released. The petition collected 34,000 signatures but publishers took no strong response to the demands. Shortly thereafter, the Public Library of Science (PLOS) was founded as an alternative to traditional publishing. PLOS ONE is currently the world’s largest journal by number of papers published (about 30,000 a year in 2015).

2002    February 14th: Release of the Budapest Open Access Initiative (BOAI), a public statement of principles relating to OA to the research literature.

2008    The National Institutes of Health (NIH) Public Access Policy, an OA mandate requiring that research papers resulting from NIH funding must be freely and publicly available through PubMed Central within 12 months of publication, is officially recorded.

2009    The Fair Copyright in Research Works Act (Bill H.R 801 IH, also known as the "Conyers Bill") is submitted as a direct response to the National Institutes of Health (NIH) Public Access Policy; intending to reverse it. The bill’s alternate name relates it to U.S Representative John Conyers (D-MI), who introduced it at the 111th United States Congress on February 3, 2009.

2012    Start of the Cost of Knowledge campaign which specifically targeted Elsevier. It was initiated by a group of prominent mathematicians who each made a commitment to not participate in publishing in Elsevier’s journals, and currently has over 15,933 co-signatories.

      Launch of PeerJ, an OA journal that charges publication fees through researcher memberships, not on a per-article basis, resulting in what has been called "a flat fee for ’all you can publish’".

2013     OSTP directive Policy memorandum (February 2013), from the Executive Office of the President/Office of Science and Technology Support (OSTP) Director John Holdren, directing US federal agencies with more than $100M in R&D expenditures to develop plans to make the published results of federally funded research freely available to the public within one year of publication and requiring researchers to better account for and manage the digital data resulting from federally funded scientific research.

2014    First OpenCon in Washington DC, an annual conference for students and early career researchers on Open Access, Open Data, and Open Educational resources.

2017    Unpaywall Button launched

2018    cOAlition-S published Plan S, a set of principles with the goal of making all research freely and openly available was formed. Initially comprised of 12 European funding agencies cOAlition-S has expanded to more than 20 international funders.

2022 The OSTP issued an updated policy (the Holdren Nelson memo) that will make taxpayer-funded research immediately available – with no embargo period – for the public to access and use, strengthening the 2013 policy. It requires large federal agencies to develop public access plans for the articles and data that result from their support. The guidance eliminates the optional 12-month embargo period for sharing papers in repositories and requires that data underlying research in peer-reviewed articles also be made immediately open.

Largely taken from Cold Spring Harbor Library