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.

Bitcoin Interest is a fork of the Bitcoin protocol that pays coin holders interest. Bitcoin Interest (BCI) allows users to securely earn interest payments without ever moving coins from their wallets. Bitcoin Interest's developers believe that paying interest, weekly or monthly, on inactive crypto-funds can benefit the entire cryptocurrency market by reducing volatility.
Bitcoin Interest (BCI) is the first cryptocurrency protocol to use the ProgPoW consensus algorithm. ProgPoW is a Proof-of-Work algorithm designed to reduce the centralizing tendencies of ASIC mining by making it easier for standard GPU devices to participate in the mining process.

Viacoin is an open source cryptocurrency based on the Bitcoin protocol. Viacoin has a 24 second block time and relatively fast transaction times. It can handle 175 transactions per second without scaling through Segwit or the Lightning Network. The fast transaction times make Viacoin a good option for sending micropayments. The platform also enables users to perform cross-chain atomic swaps between different cryptocurrencies, without a centralized exchange. Viacoin has an Auxiliary Proof-of-Work (AuxPoW) consensus mechanism that allows miners to mine multiple coins, that use the Scrypt algorithms, at the same time. Viacoin's smart contract platform, Rootstock, is compatible with Ethereum smart contracts.