BASE is one of the world's most voluminous search engines especially for academic web resources. BASE provides more than 150 million documents from more than 7,000 sources. You can access the full texts of about 60% of the indexed documents for free (Open Access). BASE is operated by Bielefeld University Library.We are indexing the metadata of all kinds of academically relevant resources – journals, institutional repositories, digital collections etc. – which provide an OAI interface and use OAI-PMH for providing their contents (see our Golden Rules for Repository Managers).The index is continuously enhanced by integrating further sources (you can suggest a source which is not indexed yet). We are working on several new features like a claiming service for authors within the ORCID DE project.BASE is a registered OAI service provider. Database managers can integrate the BASE index into their local infrastructure (e.g. meta search engines, library catalogues). Further on there are several tools and services for users, database and repository managers.