The FAST-fluorogen reporting system is used in fluorescence microscopy, flow cytometry and any other fluorometric methods to explore the living world, including biosensors and protein trafficking.  FAST has been reported for dynamic imaging of biofilms because of its unique capacity of fluorescence in low-oxygen conditions.  For the same reason it allows for imaging and FACSing anaerobes, such as Clostridium, used for biomass fermentation like the ABE fermentation.  FAST has also been reported for super-resolution microscopy of living cells.
A number of fluorogens were developed for FAST and its derivates by The Twinkle Factory, varying by their emission wavelength, their brightness and their tag affinity.  Some are non permeant, i.e., they cant go through cell membranes, hence specifically labeling membrane proteins or extracellular proteins, allowing for, e.g.', monitoring trafficking from synthesis until excretion.