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.

Gulden is a Dutch cryptocurrency based on a native blockchain with a Proof-of-Work (PoW) consensus mechanism. Gulden has gained traction in the Netherlands, where it can be used to make P2P payments, as well as send funds to an IBAN account. Gulden's marketing efforts emphasize the network's security and faster transaction times. Gulden's PoW² consensus combines aspects of PoS with PoW, and allows witnesses to add transactions to blocks after they have been mined. The network is powered by the NLG coin.

The Amp token is a digital collateral token that is specifically designed to enable the decentralized collateralization of digital asset transactions. It evolved from what was previously known as the Flexacoin network, and is meant to allow the token to better facilitate recent innovations related to borrowing and lending in the DeFi space. The Amp token's supply was created by burning the existing supply of Flexacoins, which were exchanged for the new token at a rate of 1:1. Amp will improve upon Flexacoin’s collateralization features with a new architecture that will allow for the implementation of additional on-chain supply operations and more collateral-related DeFi options.