RChain is building a cross-chain blockchain platform that hopes to improve transaction speeds and scalability. RChain smart contracts are written in Rholang and are run concurrently on the Rho Virtual Machine. Rholang stands for reflective higher-order language, and supports internal concurrent programming to improve smart contract processing.
Rchain supports multiple blockchains on the same node, allowing them to interact and enabling secure cross-chain exchanges of value. It uses a Proof of Stake consensus algorithm and a form of compression called LADL (Logic as a Distributive Law) that is meant to improve DApp performance.
Unlike most blockchains that use public keys to distinguish virtual address spaces, RChain divides its virtual address space into namespaces A namespace is a set of named channels that are used to communicate the location of a network resource. Namespaces allow smart contracts on one blockchain to be visible to system contracts elsewhere on the network. Namespace developers can also use tools and properties to improve system encryption and protocols.
The platform is powered by the RHOC token.

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.