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.

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.

Bytom is a Chinese company that is developing a blockchain platform that is specifically designed to register securities and physical assets to the Bytom blockchain. Bytom aims to create a secondary markets for these blockchain registered assets and will allow them to be tokenized.
Bytom is compatible with other platforms and enables high transaction speeds and anonymity.
One of Bytom's key features is its improved PoW consensus algorithm that is compatible with AI-enhanced ASIC chips. This allows for more efficient mining that uses less energy.