Open access

Open access is a set of principles and a range of practices through which research outputs are distributed online, free of cost or other access barriers. With open access strictly defined, or libre open access, barriers to copying or reuse are also reduced or removed by applying an open license for copyright.
The main focus of the open access movement is "peer reviewed research literature." Historically, this has centered mainly on print-based academic journals. Whereas conventional journals cover publishing costs through access tolls such as subscriptions, site licenses or pay-per-view charges, open-access journals are characterised by funding models which do not require the reader to pay to read the journal's contents. Open access can be applied to all forms of published research output, including peer-reviewed and non peer-reviewed academic journal articles, conference papers, theses, book chapters, monographs, and images.


There are a number of variants of open access publishing and different publishers may use one or more of these variants.

Colour naming system

Different open access types are currently commonly described using a colour system. The most commonly recognised names are "green", "gold", and "hybrid" open access; however, a number of other models and alternative terms are also used.

Gold OA

In the gold OA model, the publisher makes all articles and related content available for free immediately on the journal's website, usually by requiring the author rather than the reader to bear the costs of publication. In such publications, articles are licensed for sharing and reuse via creative commons licenses or similar.
The minority of gold open access journals which charge APCs are said to follow an "author-pays" model.

Green OA

by authors is permitted under green OA. Independently from publication by a publisher, the author also posts the work to a website controlled by the author, the research institution that funded or hosted the work, or to an independent central open repository, where people can download the work without paying.
Green OA is gratis for the author. Some publishers may charge a fee for an additional service such as a free license on the publisher-authored copyrightable portions of the printed version of an article.
If the author posts the near-final version of their work after peer review by a journal, the archived version is called a "postprint". This can be the accepted manuscript as returned by the journal to the author after successful peer review.

Hybrid OA

s contain a mixture of open access articles and closed access articles. A publisher following this model is partially funded by subscriptions, and only provide open access for those individual articles for which the authors pay a publication fee.

Bronze OA

Bronze open access articles are free to read on the publisher page, but lack a clearly identifiable license. Such articles may not be available for reuse.

Diamond/platinum OA

Journals which publish open access without charging authors article processing charges are sometimes referred to as diamond or platinum OA. Since they do not charge either readers or authors directly, such publishers often require funding from external sources such as academic institutions, learned societies, philanthropists or government grants.

"Black" OA

The growth of unauthorized digital copying by large-scale copyright infringement has enabled free access to paywalled literature. In some ways this is a large-scale technical implementation of pre-existing practice, whereby those with access to paywalled literature would share copies with their contacts. However, the increased ease and scale from 2010 onwards have changed how many people treat subscription publications.

Gratis and libre

Similar to the free content definition, the terms 'gratis' and 'libre' were used in the BOAI definition to distinguish between free to read versus free to reuse. Gratis open access refers to online access free of charge, and libre open access refers to online access free of charge plus some additional re-use rights. Libre open access covers the kinds of open access defined in the Budapest Open Access Initiative, the Bethesda Statement on Open Access Publishing and the Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities. The re-use rights of libre OA are often specified by various specific Creative Commons licenses; almost all of these require attribution of authorship to the original authors. In 2012, the number of works under libre open access was considered to have been rapidly increasing for a few years, though most open access mandates did not enforce any copyright license and it was difficult to publish libre gold OA in legacy journals. However, there are no costs nor restrictions for green libre OA as preprints can be freely self-deposited with a free license, and most open access repositories use Creative Commons licenses to allow reuse.


is an acronym for 'findable, accessible, interoperable and reuseable', intended to more clearly define what is meant by the term 'open access' and make the concept easier to discuss. Initially proposed in March 2016, it has subsequently been endorsed by organisations such as the European commission and the G20.


The emergence of open science or open research has brought to light a number of controversial and hotly-debated topics.
Scholarly publishing invokes various positions and passions. For example, authors may spend hours struggling with diverse article submission systems, often converting document formatting between a multitude of journal and conference styles, and sometimes spend months waiting for peer review results. The drawn-out and often contentious societal and technological transition to Open Access and Open Science/Open Research, particularly across North America and Europe has led to increasingly entrenched positions and much debate.
The area of scholarly practices increasingly see a role for policy-makers and research funders giving focus to issues such as career incentives, research evaluation and business models for publicly funded research. Plan S and AmeliCA caused a wave of debate in scholarly communication around 2019.


Subscription-based publishing typically requires transfer of copyright from authors to the publisher so that the latter can monetise the process via dissemination and reproduction of the work. With OA publishing, typically authors retain copyright to their work, and license its reproduction to the publisher. Retention of copyright by authors can support academic freedoms by enabling greater control of the work or licensing agreements.
The most commons licenses used in open access publishing are Creative Commons. The widely used CC BY license is one of the most permissive, only requiring attribution to be allowed to use the material. A range of more restrictive creative commons licenses are also used. More rarely, some of the smaller academic journals use custom open access licenses. Some publishers use "author nominal copyright" for OA articles, where the author retains copyright in name only and all rights are transferred to the publisher.


Since open access publication does not charge readers, there are many financial models used to cover costs by other means. Open access can be provided by commercial publishers, who may publish open access as well as subscription-based journals, or dedicated open-access publishers such as Public Library of Science and BioMed Central.
Advantages and disadvantages of open access have generated considerable discussion amongst researchers, academics, librarians, university administrators, funding agencies, government officials, commercial publishers, editorial staff and society publishers. Reactions of existing publishers to open access journal publishing have ranged from moving with enthusiasm to a new open access business model, to experiments with providing as much free or open access as possible, to active lobbying against open access proposals. There are many publishers that started up as open access-only publishers, such as PLOS, Hindawi Publishing Corporation, Frontiers in... journals, MDPI and BioMed Central.

Article processing charges

Some open access journals generate revenue by charging publication fees in order to make the work openly available at the time of publication. The money might come from the author but more often comes from the author's research grant or employer. While the payments are typically incurred per article published, some journals apply them per manuscript submitted or per author.
Charges typically range from $1,000–$2,000 but can be under $10 or over $5,000. APCs vary greatly depending on subject and region and are most common in scientific and medical journals, and lowest in arts and humanities journals. APCs also can also depend on a journal's impact factor. Some publishers have released estimates of their direct and indirect costs that set their APCs. Hybrid OA generally costs more than gold OA and can offer a lower quality of service. A particularly controversial practice in hybrid open access journals is "double dipping", where both authors and subscribers are charged.
By comparison, journal subscriptions equate to $3,500–$4,000 per article published by an institution, but are highly variable by publisher. This has led to the assessment that there is enough money "within the system" to enable full transition to OA. However, there is ongoing discussion about whether the change-over offers an opportunity to become more cost-effective or promotes more equitable participation in publication. Concern has been noted that increasing subscription journal prices will be mirrored by rising APCs, creating a barrier to less financial privileged authors. Some gold OA publishers will waive all or part of the fee for authors from less developed economies. Steps are normally taken to ensure that peer reviewers do not know whether authors have requested, or been granted, fee waivers, or to ensure that every paper is approved by an independent editor with no financial stake in the journal. The main argument against requiring authors to pay a fee, is the risk to the peer review system, diminishing the overall quality of scientific journal publishing.

Subsidized or no-fee

No-fee open access journals, also known as "platinum" or "diamond" do not charge either readers or authors. These journals use a variety of business models including subsidies, advertising, membership dues, endowments, or volunteer labour. Subsidising sources range from universities, libraries and museums to foundations, societies or government agencies. Some publishers may cross-subsidise from other publications or auxiliary services and products. For example, most APC-free journals in Latin America are funded by higher education institutions and are not conditional on institutional affiliation for publication. Conversely, Knowledge Unlatched crowdsources funding in order to make monographs available open access.
Estimates of prevalence vary, but approximately 10,000 journals without APC are listed in DOAJ and the Free Journal Network. APC-free journals tend to be smaller and more local-regional in scope. Some also require submitting authors to have a particular institutional affiliation.

Preprint use

A "preprint" is typically a version of a research paper that is shared on an online platform prior to, or during, a formal peer review process. Preprint platforms have become popular due to the increasing drive towards open access publishing and can be publisher- or community-led. A range of discipline-specific or cross-domain platforms now exist.

Effect of preprints on later publication

A persistent concern surrounding preprints is that work may be at risk of being plagiarised or "scooped" – meaning that the same or similar research will be published by others without proper attribution to the original source – if publicly available but not yet associated with a stamp of approval from peer reviewers and traditional journals. These concerns are often amplified as competition increases for academic jobs and funding, and perceived to be particularly problematic for early-career researchers and other higher-risk demographics within academia.
However, preprints, in fact, protect against scooping. Considering the differences between traditional peer-review based publishing models and deposition of an article on a preprint server, "scooping" is less likely for manuscripts first submitted as preprints. In a traditional publishing scenario, the time from manuscript submission to acceptance and to final publication can range from a few weeks to years, and go through several rounds of revision and resubmission before final publication. During this time, the same work will have been extensively discussed with external collaborators, presented at conferences, and been read by editors and reviewers in related areas of research. Yet, there is no official open record of that process, and if an identical or very similar paper were to be published while the original was still under review, it would be impossible to establish provenance.
Preprints provide a time-stamp at the time of publication, which helps to establish the "priority of discovery" for scientific claims. This means that a preprint can act as proof of provenance for research ideas, data, code, models, and results. The fact that the majority of preprints come with a form of permanent identifier, usually a digital object identifier, also makes them easy to cite and track. Thus, if one were to be "scooped" without adequate acknowledgement, this would be a case of academic misconduct and plagiarism, and could be pursued as such.
There is no evidence that "scooping" of research via preprints exists, not even in communities that have broadly adopted the use of the arXiv server for sharing preprints since 1991. If the unlikely case of scooping emerges as the growth of the preprint system continues, it can be dealt with as academic malpractice. ASAPbio includes a series of hypothetical scooping scenarios as part of its preprint FAQ, finding that the overall benefits of using preprints vastly outweigh any potential issues around scooping. Indeed, the benefits of preprints, especially for early-career researchers, seem to outweigh any perceived risk: rapid sharing of academic research, open access without author-facing charges, establishing priority of discoveries, receiving wider feedback in parallel with or before peer review, and facilitating wider collaborations.


The "green" route to OA refers to author self-archiving, in which a version of the article is posted online to an institutional and/or subject repository. This route is often dependent on journal or publisher policies, which can be more restrictive and complicated than respective "gold" policies regarding deposit location, license, and embargo requirements. Some publishers require an embargo period before deposition in public repositories, arguing that immediate self-archiving risks loss of subscription income.

Embargo periods

are imposed by between 20-40% of journals, during which time an article is paywalled before permitting self-archiving or releasing a free-to-read version. Embargo-free self-archiving has not been shown to affect subscription revenue, and tends to increase readership and citations. Embargoes have been lifted on particular topics for either limited times or ongoing. Plan S includes zero-length embargoes on self-archiving as a key principle.


Open access began to be sought and provided worldwide by researchers when the possibility itself was opened by the advent of Internet and the World Wide Web. The momentum was further increased by a growing movement for academic journal publishing reform, and with it gold and libre OA.
The premises behind open access publishing are that there are viable funding models to maintain traditional peer review standards of quality while also making the following changes:
An obvious advantage of open access journals is the free access to scientific papers regardless of affiliation with a subscribing library and improved access for the general public; this is especially true in developing countries. Lower costs for research in academia and industry have been claimed in the Budapest Open Access Initiative, although others have argued that OA may raise the total cost of publication, and further increase economic incentives for exploitation in academic publishing. The open access movement is motivated by the problems of social inequality caused by restricting access to academic research, which favor large and wealthy institutions with the financial means to purchase access to many journals, as well as the economic challenges and perceived unsustainability of academic publishing.

Stakeholders and concerned communities

The intended audience of research articles is usually other researchers. Open access helps researchers as readers by opening up access to articles that their libraries do not subscribe to. One of the great beneficiaries of open access may be users in developing countries, where currently some universities find it difficult to pay for subscriptions required to access the most recent journals. Some schemes exist for providing subscription scientific publications to those affiliated to institutions in developing countries at little or no cost. All researchers benefit from open access as no library can afford to subscribe to every scientific journal and most can only afford a small fraction of them – this is known as the "serials crisis".
Open access extends the reach of research beyond its immediate academic circle. An open access article can be read by anyone – a professional in the field, a researcher in another field, a journalist, a politician or civil servant, or an interested layperson. Indeed, a 2008 study revealed that mental health professionals are roughly twice as likely to read a relevant article if it is freely available.

Research funders and universities

agencies and universities want to ensure that the research they fund and support in various ways has the greatest possible research impact. As a means of achieving this, research funders are beginning to expect open access to the research they support. Many of them have already adopted open access mandates, and others are on the way to do so.
In the US, the 2008 NIH Public Access Policy, an open access mandate was put into law, and required that research papers describing research funded by the National Institutes of Health must be available to the public free through PubMed Central within 12 months of publication.


A growing number of universities are providing institutional repositories in which their researchers can deposit their published articles. Some open access advocates believe that institutional repositories will play a very important role in responding to open access mandates from funders.
In May 2005, 16 major Dutch universities cooperatively launched DAREnet, the Digital Academic Repositories, making over 47,000 research papers available. From 2 June 2008, DAREnet has been incorporated into the scholarly portal NARCIS. By 2019, NARCIS provided access to 360,000 open access publications from all Dutch universities, KNAW, NWO and a number of scientific institutes.
In 2011, a group of universities in North America formed the Coalition of Open Access Policy Institutions. Starting with 21 institutions where the faculty had either established an open access policy or were in the process of implementing one, COAPI now has nearly 50 members. These institutions' administrators, faculty and librarians, and staff support the international work of the Coalition's awareness-raising and advocacy for open access.
In 2012, the Harvard Open Access Project released its guide to good practices for university open-access policies, focusing on rights-retention policies that allow universities to distribute faculty research without seeking permission from publishers. Rights retention is currently being explored in the UK by UKSCL.
In 2013 a group of nine Australian universities formed the Australian Open Access Strategy Group to advocate, collaborate, raise awareness, and lead and build capacity in the open access space in Australia. In 2015, the group expanded to include all eight New Zealand universities and was renamed the Australasian Open Access Support Group. It was then renamed the , highlighting its emphasis on strategy. The awareness raising activities of the AOASG include presentations, workshops, blogs, and a on open access issues.

Libraries and librarians

As information professionals, librarians are often vocal and active advocates of open access. These librarians believe that open access promises to remove both the price barriers and the permission barriers that undermine library efforts to provide access to the scholarly record, as well as helping to address the serials crisis. Many library associations have either signed major open access declarations, or created their own. For example, IFLA have produced a Statement on Open Access.
Librarians also lead education and outreach initiatives to faculty, administrators, and others about the benefits of open access. For example, the Association of College and Research Libraries of the American Library Association has developed a Scholarly Communications Toolkit. The Association of Research Libraries has documented the need for increased access to scholarly information, and was a leading founder of the Scholarly Publishing and Academic Resources Coalition.
At most universities, the library manages the institutional repository, which provides free access to scholarly work by the university's faculty. The Canadian Association of Research Libraries has a program to develop institutional repositories at all Canadian university libraries.
An increasing number of libraries provide publishing or hosting services for open access journals, with the Library Publishing Coalition as a membership organisation.
In 2013, open access activist Aaron Swartz was posthumously awarded the American Library Association's James Madison Award for being an "outspoken advocate for public participation in government and unrestricted access to peer-reviewed scholarly articles". In March 2013, the entire editorial board and the editor-in-chief of the Journal of Library Administration resigned en masse, citing a dispute with the journal's publisher. One board member wrote of a "crisis of conscience about publishing in a journal that was not open access" after the death of Aaron Swartz.
The pioneer of the open access movement in France and one of the first librarians to advocate the self-archiving approach to open access worldwide is Hélène Bosc. Her work is described in her "15-year retrospective".


Open access to scholarly research is argued to be important to the public for a number of reasons. One of the arguments for public access to the scholarly literature is that most of the research is paid for by taxpayers through government grants, who therefore have a right to access the results of what they have funded. This is one of the primary reasons for the creation of advocacy groups such as The Alliance for Taxpayer Access in the US. Examples of people who might wish to read scholarly literature include individuals with medical conditions and serious hobbyists or 'amateur' scholars who may be interested in specialized scientific literature. Additionally, professionals in many fields may be interested in continuing education in the research literature of their field, and many businesses and academic institutions cannot afford to purchase articles from or subscriptions to much of the research literature that is published under a toll access model.
Even those who do not read scholarly articles benefit indirectly from open access. For example, patients benefit when their doctor and other health care professionals have access to the latest research. As argued by open access advocates, open access speeds research progress, productivity, and knowledge translation. Every researcher in the world can read an article, not just those whose library can afford to subscribe to the particular journal in which it appears. Faster discoveries benefit everyone. High school and junior college students can gain the information literacy skills critical for the knowledge age. Critics of the various open access initiatives claim that there is little evidence that a significant amount of scientific literature is currently unavailable to those who would benefit from it. While no library has subscriptions to every journal that might be of benefit, virtually all published research can be acquired via interlibrary loan. Note that interlibrary loan may take a day or weeks depending on the loaning library and whether they will scan and email, or mail the article. Open access online, by contrast is faster, often immediate, making it more suitable than interlibrary loan for fast-paced research.

Low-income countries

In developing nations, open access archiving and publishing acquires a unique importance. Scientists, health care professionals, and institutions in developing nations often do not have the capital necessary to access scholarly literature, although schemes exist to give them access for little or no cost. Among the most important is HINARI, the Health InterNetwork Access to Research Initiative, sponsored by the World Health Organization. HINARI, however, also has restrictions. For example, individual researchers may not register as users unless their institution has access, and several countries that one might expect to have access do not have access at all .
Many open access projects involve international collaboration. For example, the SciELO, is a comprehensive approach to full open access journal publishing, involving a number of Latin American countries. Bioline International, a non-profit organization dedicated to helping publishers in developing countries is a collaboration of people in the UK, Canada, and Brazil; the Bioline International Software is used around the world. Research Papers in Economics, is a collaborative effort of over 100 volunteers in 45 countries. The Public Knowledge Project in Canada developed the open-source publishing software Open Journal Systems, which is now in use around the world, for example by the African Journals Online group, and one of the most active development groups is Portuguese. This international perspective has resulted in advocacy for the development of open-source appropriate technology and the necessary open access to relevant information for sustainable development.



Various studies have investigated the extent of open access. A study published in 2010 showed that roughly 20% of the total number of peer-reviewed articles published in 2008 could be found openly accessible. Another study found that by 2010, 7.9% of all academic journals with impact factors were gold open access journals and showed a broad distribution of Gold Open Access journals throughout academic disciplines. A study of random journals from the citations indexes AHSCI, SCI and SSCI in 2013 came to the result that 88% of the journals were closed access and 12% were open access. In August 2013, a study done for the European Commission reported that 50% of a random sample of all articles published in 2011 as indexed by Scopus were freely accessible online by the end of 2012. A 2017 study by the Max Planck Society put the share of gold access articles in pure open access journals at around 13 percent of total research papers.
In 2009, there were approximately 4,800 active open access journals, publishing around 190,000 articles. As of February 2019, over 12,500 open access journals are listed in the Directory of Open Access Journals.
Walt Crawford's report on Gold Open Access 2013-2018 found that in 2018 over 700,000 articles were published in gold open access in the world, of which 42% was in journals with no author-paid fees. The figure varies significantly depending on region and kind of publisher: 75% if university-run, over 80% in Latin America, but less than 25% in Western Europe. However, Crawford's study did not count open access articles published in "hybrid" journals. More comprehensive analyses of the scholarly literature suggest that this resulted in a significant underestimation of the prevalence of author-fee-funded OA publications in the literature. Crawford's study also found that although a minority of open access journals impose charges on authors, a growing majority of open access articles are published under this arrangement, particularly in the science disciplines.
The Registry of Open Access Repositories indexes the creation, location and growth of open access open access repositories and their contents. As of February 2019, over 4,500 institutional and cross-institutional repositories have been registered in ROAR.

Effects on scholarly publishing

Article impact

Since published articles report on research that is typically funded by government or university grants, the more the article is used, cited, applied and built upon, the better for research as well as for the researcher's career.
Some professional organizations have encouraged use of open access: in 2001, the International Mathematical Union communicated to its members that "Open access to the mathematical literature is an important goal" and encouraged them to " available electronically as much of our own work as feasible" to " the reservoir of freely available primary mathematical material, particularly helping scientists working without adequate library access".


OA articles are generally viewed online and downloaded more often than paywalled articles and that readership continues for longer. Readership is especially higher in demographics that typically lack access to subscription journals. OA articles are more read on publication management programs such as Mendeley. Open access practices can reduce publication delays, an obstacle which led some research fields such as high-energy physics to adopt widespread preprint access.

Citation rate

A main reason authors make their articles openly accessible is to maximize their citation impact. Open access articles typically are typically cited more often than equivalent articles requiring subscriptions. This 'citation advantage' was first reported in 2001. Two major studies dispute this claim, however the consensus of multiple studies support the effect, with measured OA citation advantage varying in magnitude between 1.3-fold to 6-fold depending on discipline.
Citation advantage is most pronounced in OA articles in hybrid journals, and with articles deposited in green OA repositories. Articles in gold OA journals are typically cited a similar at a similar frequency to paywalled articles. Citation advantage increases the longer an article has been published.


In addition to format academic citation, other forms of research impact may be affected by OA publishing, constituting a significant "amplifier" effect for science published on such platforms. Initial studies suggest that OA articles are more referenced in blogs, on twitter, and on English Wikipedia. The OA advantage in altmetrics may be smaller than the advantage in academic citations.

Journal impact factor

measures the average number of citations of articles in a journal over a 2-year window. It is commonly used as a proxy for journal quality, expected research impact for articles submitted to that journal, and of researcher success. In subscription journals, impact factor correlates with overall citation count, however this correlation is not observed in gold OA journals.
Open access initiatives like Plan S typically call on a broader adoption and implementation of the Leiden Manifesto and the San Francisco Declaration on Research Assessment alongside fundamental changes in the scholarly communication system.

Peer review processes

of research articles prior to publishing has been common since the 18th century. Commonly reviewer comments are only revealed to the authors and reviewer identities kept anonymous. The rise of OA publishing has also given rise to experimentation in technologies and processes for peer review. Increasing transparency of peer review and quality control includes posting results to preprint servers, preregistration of studies, open publishing of peer reviews, open publishing of full datasets and analysis code, and other open science practices. It is proposed that increased transparency of academic quality control processes makes audit of the academic record easier. Additionally, the rise of OA megajournals has made it viable for their peer review to focus solely on methodology and results interpretation whilst ignoring novelty. Major criticisms of the influence of OA on peer review have included that if OA journals have incentives to publish as many articles as possible then peer review standards may fall, increased use of preprints may populate the academic corpus with un-reviewed junk and propaganda, and that reviewers may self-censor if their identity of open. Some advocates propose that readers will have increased skepticism of preprint studies - a traditional hallmark of scientific inquiry.

Predatory publishing

present themselves as academic journals but use lax or no peer review processes coupled with aggressive advertising in order to generate revenue from article processing charges from authors. In this way, predatory journals exploit the OA model by deceptively removing the main value added by the journal and parasitize the OA movement, occasionally hijacking or impersonating other journals. The rise of such journals since 2010 has damaged the reputation of the OA publishing model as a whole, especially via sting operations where fake papers have been successfully published in such journals. Although commonly associated with OA publishing models, subscription journals are also at risk of similar lax quality control standards and poor editorial policies. OA publishers therefore aim to ensure quality via auditing by registries such as DOAJ and SciELO and comply to a standardised set of conditions. A blacklist of predatory publishers is also maintained by Cabell's blacklist. Increased transparency of the peer review and publication process has been proposed as a way to combat predatory journal practices.


Databases and repositories

Multiple databases exist for open access articles, journals and datasets. These databases overlap, however each has different inclusion criteria, which typically include extensive vetting for journal publication practices, editorial boards and ethics statements. The main databases of open access articles and journals are DOAJ and PMC. In the case of DOAJ, only fully gold open access journals are included, whereas PMC also hosts articles from hybrid journals.
There are also a number of preprint servers which host articles that have not yet been reviewed as open access copies. These articles are subsequently submitted for peer review by both open access or subscription journals, however the preprint always remains openly accessible. A list of preprint servers is maintained at ResearchPreprints.
For articles that are published in closed access journals, some authors will deposit a postprint copy in an open access repository, where it can be accessed for free. Most subscription journals place restrictions on which version of the work may be shared and/or require an embargo period following the original date of publication. What is deposited can therefore vary, either a preprint or the peer-reviewed postprint, either the author's refereed and revised final draft or the publisher's version of record, either immediately deposited or after several years. Repositories may be specific to an institution, a discipline, a scholarly society, or a funder. Although the practice was first formally proposed in 1994, self-archiving was already being practiced by some computer scientists in local FTP archives in the 1980s. The SHERPA/RoMEO site maintains a list of the different publisher copyright and self-archiving policies and the ROAR database hosts an index of the repositories themselves.

Representativeness of proprietary databases

Uneven coverage of journals in the major commercial citation index databases has strong effects on evaluating both researchers and institutions. While these databases primarily select based on process and content quality, there has been concern that their commercial nature may skew their assessment criteria and representation of journals outside of Europe and North America. However, there are not currently equal, comprehensive, multi-lingual, open source or non-commercial digital infrastructures.


Like the self-archived green open access articles, most gold open access journal articles are distributed via the World Wide Web, due to low distribution costs, increasing reach, speed, and increasing importance for scholarly communication. Open source software is sometimes used for open access repositories, :Category:Publication management software|open access journal websites, and other aspects of open access provision and open access publishing.
Access to online content requires Internet access, and this distributional consideration presents physical and sometimes financial barriers to access.
There are various open access aggregators that list open access journals or articles. ROAD synthesizes information about open access journals and is a subset of the ISSN register. SHERPA/RoMEO lists international publishers that allow the published version of articles to be deposited in institutional repositories. The Directory of Open Access Journals contains over 12,500 peer-reviewed open access journals for searching and browsing.
Open access articles can be found with a web search, using any general search engine or those specialized for the scholarly and scientific literature, such as Google Scholar, OAIster,, and CORE Many open-access repositories offer a programmable interface to query their content. Some of them use a generic protocol, such as OAI-PMH. In addition, some repositories propose a specific API, such as the arXiv API, the Dissemin API, the Unpaywall/oadoi API, or the base-search API.
In 1998, several universities founded the Public Knowledge Project to foster open access, and developed the open-source journal publishing system Open Journal Systems, among other scholarly software projects. As of 2010, it was being used by approximately 5,000 journals worldwide.
Several initiatives provide an alternative to the English language dominance of existing publication indexing systems, including Index Copernicus, SciELO and Redalyc.

Policies and mandates

Many universities, research institutions and research funders have adopted mandates requiring their researchers to make their research publications open access. For example, Research Councils UK spent nearly £60m on supporting their open access mandate between 2013 and 2016.
The idea of mandating self-archiving was raised at least as early as 1998. Since 2003 efforts have been focused on open access mandating by the funders of research: governments, research funding agencies, and universities. Some publishers and publisher associations have lobbied against introducing mandates.
In 2002, the University of Southampton's School of Electronics & Computer Science became one of the first schools to implement a meaningful mandatory open access policy, in which authors had to contribute copies of their articles to the school's repository. More institutions followed suit in the following years. In 2007, Ukraine became the first country to create a national policy on open access, followed by Spain in 2009. Argentina, Brazil, and Poland are currently in the process of developing open access policies. Making master's and doctoral theses open access is an increasingly popular mandate by many educational institutions.


In order to chart which organisations have open access mandates, the Registry of Open Access Repository Mandates and Policies provides a searchable international database. As of February 2019, mandates have been registered by over 700 universities and over 100 research funders worldwide.
As these sorts of mandates and policies increase in prevalence, researchers may be affected by multiple policies. New tools, such as SWORD, are being developed to help authors manage sharing between repositories. UNESCO's policy document says, "In response to increasing incidents of this type, technical development work has been carried out to provide tools that enable the author to deposit an article once and for it to be copied into other repositories." There is a push to make more specific policy about allowed embargoes, rather than leaving it up to publishers.
Compliance rates with voluntary open access policies remain low. According to UNESCO's Policy guidelines for the development and promotion of open access, "Evidence has unequivocally demonstrated that to have real effect policies must be mandatory, whether institutional or funder policies. Mandatory policies at institutions succeed in accumulating content in their repositories, averaging 60% of total output after a couple of years of the policy being in place."