Bitcoin Diamond is a hardfork of Bitcoin that was created in 2017. Although the network's code preserves much of Bitcoin's original features, it aims to improve transaction speeds by implementing the Lightning network and increasing the storage capabilities of each block. The Lightning Network is a second layer payment protocol that works on the Bitcoin blockchain and is designed to place a large portion of the transaction data outside of the blockchain.

ZClassic is a privacy focused crytpocurrency that is a fork of ZCash. ZClassic enables a high degree of privacy and anonymity of transactions.The key differences between ZClassic and ZCash are the elimination of the 20% mining fee that are allocated as a "founders' reward" and the removal of ZCash's block limit, that was intended to create scarcity.

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.