Refeyn – Weighing molecules with light. The pioneer in mass photometry, Refeyn produces a disruptive new generation of analytical instruments that measure the mass of individual molecules directly in solution. Mass photometry transforms our ability to characterise the composition, structure and dynamics of biomolecules, revealing the true behaviour of molecules in their native environment. Quickly and simply, Refeyn instruments can show sample purity and homogeneity, analyse biomolecular complex assembly or disassembly, quantify strength and kinetics of complex molecular interactions, and much more. Refeyn aims to accelerate research and enable discoveries by sharing mass photometry with the global scientific community.