QuarkChain is building a blockchain with a focus on speed and scalability. They hope to significantly improve transaction times and reduce fees with an architecture that will rely on a two-layered blockchain and elastic sharding. QuarkChain uses a hybrid Proof-of-Work (PoW) consensus mechanism that is ASIC-resistant. Transactions are first confirmed on one blockchain layer, and then on the second. The network will be powered by the QKC coin.

The Matic Network is a sidechain based scaling solution for public blockchains. Matic aims to allow developers to better scale their Ethereum DApps by using a version of Plasma, along with side chains that use a PoS consensus mechanism. Matic plans on supporting other blockchains as well in order to facilitate interoperability.

Ubiq is an Ethereum fork that aims to create a more stable smart contract platform for building DApps. Ubiq's protocol currently uses a Proof-of-Work (PoW) consensus mechanism, but will switch to Proof-of-Stake in 2019. The network is powered by the UBQ coin.
Ubiq's goal is to create a reliable and stable platform for developing DApps by modifying Ethereum's code base with important changes that will make it more secure and reduce instability. Consensus is based on their Flux Difficulty Algorithm, which is designed to constantly adjust the hash rate to protect against network attacks.