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.

Aelf calls itself a decentralized self-evolving cloud computing network. It is a blockchain operating system that can be customized for development needs. AElf hopes to improve upon current blockchain platforms by emphasizing their unique governance system and sidechain architecture.
AElf's most important feature is its multilayer sidechains and mainchains that can be used for a variety of purposes. Each chain is dedicated to a single use case, and tasks can be distributed more efficiently across multiple chains.
AElf enables cross-chain exchanges of value and has a cross-chain messaging functionality that works with other blockchains, including Bitcoin and Ethereum. Aelf enables parallel processing of transactions that promises to improve performance.
AElf users can create private chains that operate in a similar way to the Amazon's cloud hosting service, allowing developers to utilize the private chain modules to maintain full ownership of their DApps on the Aelf computing network.
Aelf has a Delegated Proof-of-Stake consensus mechanism (dPoS). ELF token holders vote on the nodes that will become mining nodes. Those elected nodes then decide how mining incentives are distributed among stakeholders and other nodes. The number of miners on the network is equal to 2N plus 1, with N beginning at 8 and increasing by 1 every year. Miining nodes relay and confirm transactions, transfer data, and package blocks.
The ELF token is also used as a mechanism for the sidechains to be indexed on the mainchain. These indexing fees vary depending on how much the sidechains contribute to the overall ecosystem.

Ontology is a network designed to be operated across multiple blockchains. Its main focus revolves around trust issues, and it provides identity verification and reputation management capabilities. Ontology's goal is to be a platform for decentralized trust systems in businesses. Their distributed network is set up to facilitate cooperation between different projects in a trust ecosystem. Ontology's framework allows users to customize different public blockchains for different applications. Ontology has a two-token structure. ONT is the utility token of the network that can be used to generate Ontology Gas (ONG). Ontology has an innovative consensus mechanism called Verifiable Byzantine Fault Tolerance (VBFT). It combines elements of Proof-of-Stake (PoS), VRF (Verifiable Number Function), and Byzantine Fault Tolerance (BFT). The VBFT consensus mechanism will select nodes that meet certain conditions, and will verify transactions.