Figshare

All research made publicly available of Figshare gets allocated a DataCite DOI at point of publication.

How DOI find the DOI on Figshare?

You can do this at any time, with existing articles or new uploads. Starting in My data, click to edit the article and enter the metadata screen: At the bottom and to the left of the screen you'll see a new option, “Get DOI or Private Link”