In this chapter we provide an overview of the various genetically encoded fluorescent Zn2+ sensors that have been developed over the past 5 to 10 years. We focus on sensors based on Förster resonance energy transfer (FRET), as these have so far proven to be the most useful for detecting Zn2+ in biological samples. Our goal is to provide a balanced discussion of the pros and cons of the various sensors and their application in intracellular imaging. Following the description of the various sensors, several recent applications of these sensors are discussed. We end the chapter by identifying remaining challenges in this field and discussing future perspectives.