An open-access repository or open archive is a digital platform that holds research output and provides free, immediate and permanent access to research results for anyone to use, download and distribute. To facilitate open access such repositories must be interoperable according to the (OAI-PMH). Search engines harvest the content of open access repositories, constructing a database of worldwide, free of charge available research.
Open-access repositories, such as an institutional repository or disciplinary repository, provide free access to research for users outside the institutional community and are one of the recommended ways to achieve the open access vision described in the Budapest Open Access Initiative definition of open access. This is sometimes referred to as the self-archiving or "green" route to open access.
The most frequently used repository software for open-access repositories according to OpenDOAR are Digital Commons, DSpace and EPrints.) Other examples are arXiv, bioRxiv, Dryad, Figshare or Zenodo.