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.

MOAC is developing a multi-layer blockchain platform that aims to improve transaction speeds and scalability. MOAC's architecture is divided into a main chain and microchains, and uses sharding to improve network performance. This enables an asynchronous smart contract platform that increases the number of contracts that can be processed, as well as transaction speed.
MOAC's development platform allows DApp creators to choose from a variety of consensus algorithms. It also enables cross-chain exchanges of value between different blockchains.

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.