OpenDOAR (the Directory of Open Access Repositories) and ROAR (Registry of Open Access Repositories) are two similar, but unrelated web sites which list OA repositories. Given the similarity of the two projects, both will be briefly reviewed in this post.
OpenDOAR
OpenDOAR is a project of the Centre for Research Communications at the University of Nottingham in the UK. The directory currently holds information about 3182 OA repositories. The “Find” page which lists results for searches (and which can also act as a browse feature) lists a description of each repository along with its software, number of items (and last update date), subjects, content type, languages, and a list of policies. By default, this page returns summaries. Clicking the “Link to this record” link next to each repository will provide more information about its policies and a little bit more information about the repository and its institution in general, but otherwise this screen is identical to what appears on the brief results page.
Users can instead select that the results be returned as a chart, table, or Google Map. Options for charts including the number of repositories by content, country, type, and other information. These charts can be embedded in other web pages, as described by a powerpoint on the “Tools” page.
Users can also search the contents of repositories listed in OpenDOAR via a Google search page, and suggest that a new repository be added to the directory.
ROAR
ROAR is a project of the University of Southampton, also in the UK, and (as of the date of this post) lists 4322 repositories (more than OpenDOAR in part because OpenDOAR seems to have stricter weeding policies). Users can search for repositories using an on-site search page with a number of options, and can also search for content inside of repositories using a custom Google search (which, at the time of this posting, was not working). Additionally, the repositories can be browsed by country, year, type of repository, institution, and software type.
Clicking the “record details” link next to a repository’s information will provide more details, such as when the repository was created, what kind of content it contains, where it is based, and its number of records.
Beyond just listing repositories, ROAR allows you to create charts and graphical analyses, and export results in various formats. It is, for instance, possible to generate a graph showing the number of known repositories by year in a certain country or topic, making ROAR a useful tool for OA scholars. Additionally, results pages provide not just a list of how many repositories there are for a topic (etc.) but how active these repositories are, showing number of deposited records and so on.
Like many web lists, ROAR allows users to add new records. You will need to create an account if you wish to add yours to the list.
The project notes that (at this time) automated harvesting of repositories is not working correctly, so that the number of articles hosted by each repository is incorrect.
OpenDOAR or ROAR?
Both lists of repositories are slightly different in terms of what they present to the viewer. OpenDOAR seems to do a more effective job of providing a current picture of OA repositories, whereas ROAR provides a clearer picture of their historical numbers. The ROAR web site is also a bit buggy at the moment, and several features do not work properly. OpenDOAR does not seem to have this problem.
Ultimately, both are useful sites for researchers interested in finding OA content or in researching green OA.