Refeyn, the mass photometry pioneer, offers new capabilities to characterise the function, structural composition and dynamics of biomolecules. Refeyn instruments measure the mass of individual molecules directly in solution, quickly and simply revealing the true behaviour of molecules in near-native environments. The diverse applications of mass photometry include quantitative analysis of sample purity and homogeneity, biomolecular complex assembly and disassembly, the strength and kinetics of molecular interactions, and more. Refeyn was spun out of Oxford University in 2018 to make mass photometry available globally. Its technology has now been rapidly adopted across academia and industry, where it is transforming biomolecular characterisation. The TwoMP, Refeyn’s mass photometer, brings the technology into everyday laboratory life, enabling molecular measurements with unprecedented speed and simplicity. It uses proprietary technology to detect the light scattered by single molecules in solution, delivering label-free mass measurements over a broad mass range with high precision and exquisite sensitivity.