Decentralized ledger technologies distribute data and execution across a public peer-to-peer network, which allows for more democratic governance of distributed systems and enables tolerating Byzantine failures. However, current protocols for such decentralized ledgers are limited in performance as they require every participant of the protocol to execute and validate every operation. Because of this, systems such as Bitcoin or Ethereum are limited in their throughput to around 10 transaction per second. Additionally, current implementations provide virtually no privacy to individual users, which precludes decentralized ledgers from being used in many real-world applications. This thesis analyses the scalability and privacy limitations of current protocols and discusses means to improve them in detail. It then outlines two novel protocols for building decentralized ledgers, their implementation, and evaluates their performance under realistic workloads. First, it introduces the BitWeave, a blockchain protocol enabling parallel transaction validation and serialization while maintaining the same safety and liveness guarantees provided by Bitcoin. BitWeave partitions the system’s workload across multiple distinct shards, each of which then executes transactions mostly independently, while allowing for serializable cross-shard transactions. Second, it discusses DataPods, which is a database architecture and programming abstraction that combines the safety properties of decentralized systems with the scalability and confidentiality of centralized systems. Each data pod is akin to a conventional database instance with the addition of enabling users to detect and resolve misbehavior with the help of a global ledger. Further, data pods are interoperable with each other through federated transactions, enable confidentiality of data, and allow users to migrate their data in case of failure.