Ethereum Classic is the original protocol of Ethereum. As a result of the massive hack on the Ethereum-based DAO, in which around 14% of all ETH in circulation were stolen, a hard fork was proposed to return the stolen funds to their owners. This caused an ideological split revolving around the question of changing previous transactions in the blockchain. Some Ethereum holders rejected the hard fork, and decided to keep using the original protocol, based on the principle that the blockchain is immutable, and cannot be changed.

PRIZM is an open-source cryptocurrency based on the NEXT core. The PRIZM architecture is built in JAVA. It has a Proof-of-Stake (PoS) consensus mechanism that varies slightly from other PoS algorithms. It is designed to be more resistant to attacks against the network. PRIZM has developed the concept of paramining, which helps the network achieve consensus and encourages community participation.

Quantum Resistant Ledger is developing an enterprise blockchain platform that is designed to be secure against an attack from quantum computers. The Quantum Resistant Ledger (QRL) implements a more secure type of cryptographic signatures call XMSS. The network has a Proof of Stake consensus mechanism.