Starting with OSF Preprints, SocArXiv, PsyArXiv, BITSS, EngrXiv, PaleorXiv, SportrXiv, Thesis Commons, MarXiv, INarXiv, NutriXiv, EarthArxiv, and the newest member of the community AfricArxiv, annotation on preprints is now enabled using the Hypothesis platform.
Annotation will increase transparency in scientific practices by enabling researchers to collaborate, discuss research with peers, and share additional information directly on preprints both before and after they are posted. The partnership builds on the foundations laid by the publication of web annotation as a standard by the W3C, the pioneering work by Hypothesis to build an open annotation infrastructure, and by COS to offer OSF, a comprehensive platform for open scientific research and publication.
The official release from Hypothesis is here.