Open Access

These directories can be used to help discover OA publications:

• Directory of Open Access Journals A directory of over 5000 academic, peer reviewed OA journals (almost 2300 of which are article searchable). 
• Directory of Open Access Books A directory of over 30,000 academic, peer reviewed OA books
• OpenDOAR Directory of academic Open Access repositories.
• OAIster search engine A collection of academically-oriented digital resources searchable by anyone.
• Registry of Open Access Repositories, ROAR
• Networked Digital Library of Theses and Dissertations
  An international organization dedicated to promoting the creation, dissemination and preservation of electronic theses and dissertations.
• Open Access Map
  The Open Access Map displays the locations of all types of OA-related initiatives, including funding policies, government documents, university mandates, repositories, and Open Access journals.

• BioMed Central (BMC)
  Publishes more than 150 peer-reviewed open access journal.
• Public Library of Science (PLoS)
  Publishes 7 high quality scientific journals
• Hindawi Publishing
  Publishes 150+ open access journals in areas of science, technology and medicine.
• Bioline International
  Bioline International is a not-for-profit electronic publishing service committed to providing open access to quality research journals published in developing countries.
• PubMed Central
  The U.S. National Institutes of Health (NIH) free digital archive of biomedical and life sciences journal literature.
• Oxford Journals Publishes three OA journals: Nucleic Acids Research, Evidence-Based Complementary & Alternative Medicine and DNA Research.
• American Institute of Physics Publishes one OA journal: Biomicrofluidics
• Emerald Engineering are piloting a new OA program called Emerald Asset. There are no publication fees; "In exchange for open publication authors will be asked to submit a summary of their research findings highlighting their practical application."

These publishers give authors the option to pay a fee to make their article immediately open access, although the publisher still retains copyright. This hybrid model of open access does not always apply to the publisher's full suite of journals.

• American Chemical Society
• American Physical Society
• Blackwell Publishing
• Cambridge University Press
• Company of Biologists
• Elsevier
• Karger
• Oxford Journals
• PNAS
• Springer
• Taylor & Francis
• Wiley

Many publishers hosted by HighWire Press offer free access to the back-files of biomedical journals.

Sherpa/RoMEO is a searchable database of publisher policies on the self-archiving of journal articles on the web and in Open Access repositories. The archiving rights policy for each publisher's entry is coded according to a colour category.

• green  can archive pre-print amd post-print or publisher's version / PDF
• blue    can archive post-print (i.e. final draft post-refereeing) or publisher's version/PDF
• yellow  can archive pre-print (i.e. pre-refereeing)
• white   archiving not formally supported

All open access journals allow archiving and can be taken as RoMEO "green".  "Gold" is not a RoMEO colour category, but is often used to describe publishers of open access journals.