For purposes of this page, data repositories are sites where researchers can store, retrieve, and, most importantly, share their raw research data. They are not to be confused with data collections, in which editors assemble and organize data from a variety of sources (e.g. Reaxys, CRC Handbook of Chemistry and Physics, etc.)
For more information on data management for researchers, see the Research Data Management guide.
To locate datasets other than the ones listed below, try the Google Dataset Search.