Horizen, formerly called ZenCash, is a cryptocurrency focused on privacy. Horizen has an end-to-end-encryption system with zero-knowledge technology, that allows for anonymous transactions and messaging.
The company suffered a 51% attack in June, 2018 and has since re-branded as Horizen. Horizen hopes to combine anonymous transactions and messaging with an emphasis on community governance.

Boolberry is a Proof-of-Work privacy coin designed to enable completely anonymous financial transactions. Boolberry's architecture reduces block size to improve transactions times, and has a mining algorithm that is ASIC resistant.

Stealth is a cryptocurrency focused on privacy and and speed. The Stealth blockchain has a Quantum Proof-of-Stake (qPoS) consensus mechanism that is designed to enable almost instant transactions with improved privacy. Validators on the network are assigned a short quantum of time to validate transactions. The protocol combines two types of blockchain ledgers, for different types of transactions, to improve validation speeds on their platform. The network is powered by the XST coin.