Directory of Open Access Journals - also policies, best practices, etc.
Our current system for communicating research uses a print-based model in the digital age. Even though research is largely produced with public dollars by researchers who share it freely, the results are hidden behind technical, legal, and financial barriers….Open Access is the free, immediate, online availability of research articles combined with the rights to use these articles fully in the digital environment… (SPARC)
Directory of Open Access Repositories - is the quality-assured global directory of academic open access repositories. It enables the identification, browsing and search for repositories, based on a range of features, such as location, software or type of material held.
ArXiv - An online repository of scientific papers in mathematics, physics, astronomy, electrical engineering, computer science, quantitative biology, statistics, mathematical finance and economics. Papers here are typically posted without peer review. ArXiv inspired a variety of derivative repositories for other fields of study including SocArXiv, PsyArXiv, and bioRxiv
PubDefense - Provides access to journal articles and conference papers that are the result of DoD and ODNI/IARPA-funded research.