The Polkadot blockchain is a multi-chain blockchain that is designed to bundle multiple chains together so that they can be executed in parallel. The goal is for every block on the Polkadot blockchain to contain multiple blocks from other chains. This will enable the network to contain the transaction information from multiple chains and dramatically increase the overall interoperability between different blockchain networks. Polkadot was created by the Web3 Foundation, which is led by Gavin Wood, one of the founders of Ethereum. Polkadot is their flagship project, and aims to solve the issues in the blockchain ecosystem related to disjointed governance and interoperability.

ArcBlock is creating a blockchain ecosystem for building decentralized applications. Their goal is to provide consumers with the framework and tools to use decentralized apps as easily as current web-based versions. ArcBlock was founded by Robert Mao and Flavien Charlton, who also created Colored Coins, Open Assets Protocol and Openchain.
ArcBlock's Open Chain Access Protocol gives developers an abstract layer for using underlying blockchains. It has a serverless computing architecture that supports various types of applications. ArcBlock is based on the Blocknet application protocol that executes smart contracts and can access external data sources. Blocknet's design and open chain access protocol provide a layer for accessing multiple blockchains.

Hshare is the token that was released in an ICO for the development of the Hcash (Hyper Cash) project. Hcash will be a dual-chain cryptocurrency that will have a side chain for both blockchain-based and other decentralized networks. Hcash is a community driven platform that is designed to exchange value and data across these platforms. Hcash's dual sidechain consists of a blockchain and a Directed Acyclic Graph (DAG) network. It's designed to facilitate exchanges of value between blockchain-based and non-blockchain decentralized systems with a high degree of privacy and encryption. Hcash's dual networks will offer addresses that are inter-operable with other common cryptocurrencies, allowing users to send and receive various currencies in their Hcash wallet.
Hcash has a hybrid PoW and PoS consensus algorithm that combines verification and governance features of both mechanisms.