SSRN is a platform for the dissemination of early-stage research. From its initial focus on the social sciences in 1994, SSRN has grown to become the most interdisciplinary service of its kind, representing disciplines across the full research spectrum, including the applied sciences, health sciences, humanities, life sciences, physical sciences, and social sciences. SSRN is instrumental both as a starting point for students and faculty in the research process, and as a place to communicate their findings at an early stage, prior to publication in academic journals.
SSRN is a searchable online library that enables authors to post their papers and abstracts easily and free of charge. The vast majority of papers can be downloaded free of charge as well. The only exceptions are papers whose copyright is held by third parties that request a download fee. SSRN provides a space for a variety of content types to be accessed beyond the traditional research article, including gray literature, book reviews, multimedia files, and datasets.
While many preprint servers operate as content repositories, SSRN maximizes usage and discoverability by classifying papers into topic-based eJournals that are distributed to individual and institutional subscribers. This results in downloads and citations that SSRN aggregates into meaningful metrics that authors use for promotion and tenure purposes and that institutions use in their hiring and ranking activities
For more information about SSRN; https://www.ssrn.com/index.cfm/en/ssrn-faq/