Qtum has been described as a hybrid between Ethereum and Bitcoin. Qtum is a smart contracts platform that places a strong focus on value transfers as well as decentralized apps. Qtum enables users to create smart contracts on the platform and conduct cryptocurrency transactions.
Qtum has a Proof-of-Stake (PoS) consensus algorithm. Several decentralized apps are already using the platform.

Peercoin is the first Proof-of-Stake (PoS) cryptocurrency. It was created in 2012 and is one of the oldest and most reliable cryptocurrency networks in the crypto sector. The protocol was developed by Sunny King and Scott Nadel, both of whom are anonymous. Sunny King also created Primecoin and VEE.
Peercoin’s PoS consensus mechanism is now widely used in the blockchain space, and allows every network participant to be both a miner or an owner. The project is focused on creating a cryptocurrency platform that will be stable, secure, energy efficient, and distributed fairly.

DigiByte is a a blockchain platform that places an emphasis on security and block speed. DigiByte has one of the fastest block speeds of any public blockchain and uses an innovative consensus protocol with 5 mining algorithms. This prevents mining centralization and also minimizes the chances of security breaches. DigiByte transactions are limited in size and scope to increase speed, efficiency, and throughput.
DigiByte hopes that these innovations will provide the ideal blockchain infrastructure for a range of applications within the IoT and AI fields, that require a high degree of security and fast block speeds.