Seeing biochemical events is essential to understand the functioning of cells and organisms. Such imaging depends on the selective targeting of fluorescent reporters and biosensors in living systems. These reporters and biosensors can be entirely synthetic, entirely genetically encoded or hybrid. Hybrid reporters and biosensors composed of a genetically encoded module that binds a fluorogenic chromophore and activates its fluorescence have recently drawn attention as they offer new opportunities for pushing the frontiers of bioimaging.