Peercoin is the first Proof-of-Stake (PoS) cryptocurrency. It was created in 2012 and is one of the oldest and most reliable cryptocurrency networks in the crypto sector. The protocol was developed by Sunny King and Scott Nadel, both of whom are anonymous. Sunny King also created Primecoin and VEE.
Peercoin’s PoS consensus mechanism is now widely used in the blockchain space, and allows every network participant to be both a miner or an owner. The project is focused on creating a cryptocurrency platform that will be stable, secure, energy efficient, and distributed fairly.

Digix is digital gold on the blockchain. By combining the historical stability of a valuable physical asset with the advantages of a distributed ledger, Digix allows users to benefit from the advantages of both commodities and digital tokens.
Digix has an innovative Proof of Asset (PoA) protocol that allows it it tokenize a physical asset. The PoA protocol tracks an asset through its chain of custody, and enables anyone to verify its existence without an intermediary. Since every DGX = 1 Gram of gold, their platform can be used as a secure and transparent digital marketplace for gold.
Digix is also behind DigixDAO, a platform that allows users to contribute to building a blockchain-based digital gold payment system. They hope to create a decentralized autonomous organization (DAO) that will participate in creating this platform. Instead of issuing shares, the organization will be run by DigixDAO token holders.

ZCoin is a privacy focused cryptocurrency built on Ethereum. The ZCoin protocol enables anonymous transactions with cryptography that utilizes Zero-Knowledge Proofs (ZKP). ZCoin increases privacy on their network by using a coin-mixer contract that wraps transactions in a serial number and destroying wrapped coins once they have been redeemed.
Zcoin was the first cryptocurrency to use a Merkle Tree Proof (MTP) as its proof of work algorithm. Merkle Tree Proofs are an innovative solution to achieving network consensus, and can increase transaction time while reducing the centralizing tendency of ASIC mining.