A preprint is a draft version of a research paper that has not yet been subject to a review. It may have already been submitted to a publisher at the same time but not yet formally peer-reviewed, but this does not have to be the case. Even though a preprint can in theory be disseminated via any medium, in practice they are often archived and disseminated on central repositories. The community members of these repositories then receive a message and can check uploaded content. There are several of these kinds of repositories or preprint servers.
Specialist repositories in the field of economics such as EconStor and RePEc offer access to preprint and working papers, and are therefore particularly interesting to search.
Cross-disciplinary repositories in which you are able to search for preprints are:
You can find further repositories using the search services for repositories.
You can find further repositories with the overview lists of repositories.