Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.

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.

Flash Coin is a cryptocurrency designed to be used for everyday transactions. Flash's blokchain has a delegate-based consensus model that depends on elected delegates to verify transactions. These delegates elect 25 Miners who create new blocks on the blockchain. Each miner is given a specific time where they can mine a block. The Flash Coin algorithm also introduces a concept called Consensus Height, which refers to the moment when more than half of elected miners have created a block on top of another block in the chain.