Contemporary blockchain-based systems achieve decentralization at the expense of privacy. In some systems, such as Bitcoin, every transaction ever made is viewable in real time by everyone in the world. It is easy to imagine this level of transparency as a deal-breaker for many blockchain use cases. Fortunately, researchers are developing new cryptographic primitives that would allow a much more favourable trade-off between decentralization and privacy. The zero-knowledge SNARK protocols embodied in the Zcash cryptocurrency are a prominent example. In this talk I list some potential real-world applications of these new protocols and I survey the state-of-the art in decentralized privacy.