Nxt is a blockchain platform developed by Jelurida, which is also developing the Ardor blockchain. Nxt's goal is to improve upon existing blockchain platforms with a modular toolset that enables users to create their own digital assets that can be listed on decentralized marketplaces. Nxt also features community driven voting mechanisms and has an architecture that separates the blockchain into parent and child blockchains.
The network is powered by the NXT token and has a Proof-of-Stake (PoS) consensus mechanism.

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.

Ignis is a blockchain platform that is being developed by Jeluirda; the company behind Ardor and Nxt. Ignis is a child chain of the Nxt blockchain. Jelurida is developing blockchain platforms that will enable users to develop decentralized applications, and will be based on a parent and child chain architecture.
Ignis allows users to create child chains with specific features and to create tokens that meet their needs. This project is closely related to Ardor and Nxt.