Interdisciplinary open access databases

DOAB (Directory of Open Access Books)
Directory of freely accessible academic e-books from all subject areas, with a particular focus on quality-assured open access monographs.

DOAJ (Directory of Open Access Journals)
International directory of open access academic journals offering free access to peer-reviewed research articles.

DOAT (Directory of Open Access Theses)
Search service for freely accessible dissertations and theses from institutional repositories worldwide.

OAIster
Interdisciplinary meta-search engine for open access publications from numerous academic repositories.

Zenodo
Repository for publications, research data, and software from all disciplines, operated by CERN.

Interdisciplinary publishing platforms (with a substantial open access portfolio)

Springer Nature Link
Platform for academic books and journals; open access content must be filtered specifically.

Wiley Online Library
Publisher platform offering journals and e-books across a wide range of disciplines; open access content must be filtered specifically.

ScienceDirect (Elsevier)
Extensive platform for scientific, social science, and medical literature; open access content must be filtered specifically.

De Gruyter Brill
Publisher platform for publications in the humanities and social sciences; already restricted to open access content.

Emerald Insight
Publisher platform for economics and social science publications; open access content must be filtered specifically.

Social sciences

SSOAR
Specialised repository for social science open access literature, including journal articles, book chapters, and working papers.

GESIS
Central infrastructure for social sciences, providing access to publications, research data, and methodological resources.

PeDOCS
Specialised repository for education and educational research, providing open access articles, books, and research reports.

SSRN (Social Science Research Network)
Platform for pre-prints and working papers in social sciences, economics, and law enabling the rapid dissemination of current research.

OAPEN Library
Platform providing free access to academic e-books, with a particular focus on the humanities and social sciences.

Staatslexikon
Academic online encyclopaedia focusing on politics, economics, society, and law.

Transcript (Open Access)
Open access publications from the Transcript publishing house, with a particular focus on the social sciences and cultural studies.

Business and economic sciences

EconStor
Open access repository of the ZBW (Leibniz Information Centre for Economics) for economics journal articles and working papers. 

EconPapers
Meta-search engine for economics literature based on RePEc.

AgEcon Search
Open access repository for agricultural and economics publications, including research articles and reports.

World Bank Open Knowledge Repository
Open access platform of the World Bank providing studies, reports, and analyses on global economic issues.

STEM (Science, technology, engineering, and mathematics)

arXiv
Pre-print server for physics, mathematics, computer science, and related disciplines, providing early access to research findings.

ChemRxiv
Pre-print server for chemistry research, enabling the dissemination of current studies prior to peer review.

ACM Digital Library (Basic)
Central database for computer science literature, including journal articles and conference proceedings; recommended to use an open access filter.

DBLP
Bibliographic database for computer science, providing links to academic publications.

IEEE Xplore
Specialised database for electrical engineering, computer science, and technology, including journal articles and conference publications; open access content must be filtered specifically.

ChemInfo
Reference for chemical substances, reactions, and their properties.

Statistics

Destatis
Portal of the Federal Statistical Office providing official statistics on Germany.

Eurostat
Statistical portal of the European Union providing comparable data for EU member states.

Our World in Data
Platform providing freely accessible data and visualisations on global social issues.