n geometrically frustrated magnets, competition between interactions can lead to unusual magnetic phases. One of the most exciting is known as a quantum spin liquid – a long-range entangled ground state with exotic, fractional excitations. The last 10 years have seen an explosion in the number of possible quantum spin liquid materials available for study, but many open questions remain. In this presentation I will review some of the experimental progress that has been made in this field, with a particular focus on magnetic resonance techniques like muon spin rotation (µSR) and nuclear magnetic resonance (NMR). I will then discuss some of my research group’s work on Mo3O8-based cluster magnets which may be best described with a 1/6th-filled breathing kagome lattice. I will show that these systems present an exciting new platform for the discovery of quantum spin liquid phases.