| 1 | ARXIV | Open access to 1,331,009 e-prints in physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science and economic subject search and browse. |
| 2 | BASE | BASE is one of the world's most voluminous search engines especially for academic web resources. BASE provides more than 240 million documents from more than 8,000 content providers. |
| 3 | CogentOA | CogentOA is a forward-thinking partner to the research communities, with journals across all areas of academia from education to engineering and medicine to mathematics. |
| 4 | Core Repositories | CORE (Connecting Repositories) gives you access to millions of scholarly articles aggregated from many open access repositories. |
| 5 | Sciendo | Sciendo, company owned by a reputable academic publisher, De Gruyter publishes open access journals (about 600 owned by other universities and institutions), books, conference proceedings, etc. for academics and professionals. |
| 6 | Directory of Open Access Journals (DOAJ) | The DOAJ aims to be comprehensive and cover all open access scientific and scholarly journals that use a quality control system to guarantee the content. |
| 7 | Digital Commons | The platform brings together free, full-text scholarly articles from hundreds of universities and colleges worldwide; curated by university librarians and their supporting institutions. It also includes a growing collection of peer-reviewed journal articles, book chapters, dissertations, working papers, conference proceedings, etc. |
| 8 | e-LIS | Established in 2003, e-LIS is an international digital repository for Library and Information Science (LIS). The development of an international LIS network has been stimulated by the extension of the open access concept to LIS works and facilitated by the dissemination of material within the LIS community. |
| 9 | EconBiz: Virtual Library for Economics and Business | The search portal that focuses on the economics and business subject area aims to support research in and teaching of economics with a central entry point for all kinds of subject-specific information and direct access to full texts. |
| 10 | Electronic Library of Mathematics | The portal contains online journals, article collections, monographs, and other electronic resources in the field of mathematics. |
| 11 | Hindawi Publishing Corporation | Offers many open access peer-reviewed articles from more than 400 journals covering a wide range of academic disciplines. |
| 12 | Internet TESL Journal | The Internet TESL Journal published articles from 1995 through 2010. This website is now an online resource book for teachers who can refer to our published articles on teaching techniques and other things of interest to EFL and ESL teachers. |
| 13 | Molecular Diversity Preservation International (MDPI) | Publishing proposals, including transfer of existing journals, launch of new titles or conversion of subscription journals to open access. |
| 14 | OMICS International | Make the best use of scientific research and information from our 700+ leading-edge peer reviewed, open access journals that operates with the help of 50,000+ editorial board members and esteemed reviewers and 1000+ Scientific associations in medical, clinical, pharmaceutical, engineering, technology, and management fields. |
| 15 | Springer Open Journals | SpringerOpen includes Springer's portfolio of 160+ peer-reviewed fully open access journals across all areas of science ranging from very specialized titles to SpringerPlus, an interdisciplinary open access journal that covers all disciplines. |
| 16 | IAENG International Journal of Computer Science (IJCS) | IAENG International Journal of Computer Science covers the frontier issues in the computer science and their applications in business, industry, and other subjects. |
| 17 | Insight Medical Publishing | Insight Medical Publishing is entirely committed to provide the most accurate and innovative source of online learning, transforming, and advancing science, health and technology. |
| 18 | Wiley Open Access Journal | Wiley Open Access publishes authoritative peer reviewed open access journals across many research disciplines such as, biological, chemical and health sciences. |
