1. Google Scholar (scholar.google.com/)
    A free academic search engine that indexes academic information from various online web resources. The Google Scholar lists information across an array of academic resources, mostly are peer-reviewed. It works in the same manner as Scirus. Founded in 2004, it is one of the widely used academic resources for researchers and scholars.
  2. CiteSeer (citeseerx.ist.psu.edu)
    A digital library and online academic journal within the field of computer science. It indexes academic resources through an autonomous citation indexing system. This academic database is particularly helpful for students seeking information on computer and information sciences. It offers many other exclusive features to facilitate the students with the research process that include: ACI – Autonomous Citation Indexing, reference linking, citation statistics, automatic metadata extraction, and related documents. Founded in 1998, it is the first online academic database and has since evolved into a more dynamic and user-friendly academic search engine.
  3. GetCITED (www.getcited.org/)
    A powerful tool in searching for scientific information. It is an online academic database that indexes academic journals and citations. It is a one-stop platform that offers everything related to academic publications such as chapters, conference papers, reports, and presentations. You can even browse through the bibliographies to search related details. Furthermore, you can find information on any author and his published works. The two ‘most outstanding’ features of this academic search engine tool include: ‘a comprehensive database’ and ‘discussion forum’. It allows every member from academia to contribute to its database resources. It has over 3,000,000 written by more than 3,00,000 authors.
  4. Microsoft Academic (academic.research.microsoft.com/)
    Yet another top search engine for academic resources. Developed by Microsoft Research, it has more than 48 million publications written by over 20 million authors. It indexes a range of scientific journals from computer science and engineering to social science and biology. It has brought in many new ways to search academic resources, such as papers, authors, conferences and journals. This academic search engine allows you to search for information based on authors or domains.
  5. Bioline International (www.bioline.org.br/)
    Among the most trusted and authentic search engines that have peer-reviewed academic journals on public health, food and nutritional security, food and medicine and biodiversity. It provides free access to peer-reviewed journals from third world countries. It promotes the exchange of ideas through academic resources. Founded in 1993, it has 70 journals across 15 countries that offer information on subjects like crop science, biodiversity, public health, and international development.
  6. Directory of Open Access Journals (www.doaj.org/)
    Director of Open Access Journals (DOAJ) is yet another free search engine for scientific and scholarly resources. The directory offers a huge range of topics within scientific areas of study. It is among the richest sources of scholarly databases with over 8,000 journals available on different topics. All the journals are thoroughly peer-reviewed.
  7. PLOS ONE (www.plosone.org/)
    Founded in 2006, PLOSE ONE provides a free access platform to everyone searching for science-related information. All the articles published in PLOS ONE on a strictly peer-reviewed process. This academic database has a meticulous procedure for publishing a journal. You can find plenty of articles and academic publications using this platform.
  8. BioOne (www.bioone.org/)
    An excellent search engine for scientific information, BioOne contains academic resources for biological, environmental and ecological sciences. Established in 2000, it started as an NGO and later became an online academic journal directory. The journal gives free access to over 25000 institutions all over the world.
  9. Science and Technology of Advanced Materials (iopscience.iop.org/1468-6996/)
    First published in 2000, the science and technology of advanced materials became online in 2008. This peer-reviewed academic journal offers free access to academic journals on major areas of science and technology. The academic directory is totally free of cost and provides easy and simple access to a plethora of information covering scientific subject-matters.
  10. New Journal of Physics (iopscience.iop.org/1367-2630)
    An online scientific search engine that has academic databases with physics as a core subject. Founded in 1998, it is co-founded by the Institute Of Physics and Deutsche Physikalische Gesellschaft. The search engine offers academic journals on diversified topics with physics as a central theme.
  11. ScienceDirect (www.sciencedirect.com/)
    A leading full-text scientific database offering journal articles and book chapters from more than 2,500 journals and almost 20,000 books.