2023 marks the 30th anniversary of the discovery of single-domain antibody fragments in camelids, better known as nanobodies. This was the starting point for their tremendous success story in biomedicine. Here we highlight recent advances in the development of nanobodies for the detection of neutralizing SARS-CoV-2 antibodies, as biosensors for monitoring extracellular metabolites and as tracer molecules for non-invasive imaging of immune cells.