Ravencoin is a blockchain created by the owner of Overstock.com. It is a use case specific blockchain for the declaration of ownership of digital assets. Ravecoin is a fork of Bitcoin, and was originally funded by Medici Ventures, a blockchain investment fund owned by Overstock.com.
Ravencoin's name is inspired by the use of Ravens in sending messages, and its blockchain is designed to carry statements of truth about who owns what asset. The developers created a new consensus algorithm called x16r to solve the problems of centralized ASIC mining. The algorithm is unique in that it consists of 16 different hashing algorithms whose order are randomly changed.

Viacoin is an open source cryptocurrency based on the Bitcoin protocol. Viacoin has a 24 second block time and relatively fast transaction times. It can handle 175 transactions per second without scaling through Segwit or the Lightning Network. The fast transaction times make Viacoin a good option for sending micropayments. The platform also enables users to perform cross-chain atomic swaps between different cryptocurrencies, without a centralized exchange. Viacoin has an Auxiliary Proof-of-Work (AuxPoW) consensus mechanism that allows miners to mine multiple coins, that use the Scrypt algorithms, at the same time. Viacoin's smart contract platform, Rootstock, is compatible with Ethereum smart contracts.

Bitcoin Cash is a cryptocurrency that was created as a result of a hard fork of the original Bitcoin blockchain that took place in 2017. Due to the open source nature of the Bitcoin protocol, and the lack of a central governing body to resolve disputes, the Bitcoin community became extremely divided about what to do about rising fees and slow transaction times. As the platform's transaction volume increased, and the associated fees to confirm them also increased dramatically, many people began advocating for a larger block size.
In mid 2017, a group of developers introduced segregated witness technology, or SegWit, that was designed to increase Bitcoin's scalability by moving some transaction details off of the blockchain. Segwit was meant to resolve the issues that revolved around the growing amount of transaction data, but many members of the Bitcoin community felt that it undermined the original vision outlined by Satoshi Nakamoto.
On August 1, 2017, they initiated a hard fork of the protocol that created Bitcoin Cash and implemented an increased block size of 8mb. At the time of the fork, bitcoin holders automatically became owners of the same number of Bitcoin Cash units. The increased block size led to faster transaction times and made Bitcoin Cash easier to use as a medium of exchange.