FN3-based monobodies selective for the receptor binding domain of the SARS-CoV-2 spike protein

•Monobodies were generated via phage-display to the SARS-CoV-2 spike protein.•Affinities of the monobodies for the RBD are estimated between 3 and 14 nM.•The monobodies bind specifically to the RBD of SARS-CoV-2 virus.•At least three different epitopes are recognized by the set of four monobodies.•Fc fusions to the monobodies bind well to the RBD.