Cardstack is a blockchain technology company that is developing an open-source framework and consensus protocol to make blockchains more usable and scalable. Their goal is to create a decentralized modular smart contract ecosystem. The Cardstack network is powered by the Ethereum-based CARD token.

TrueChain is developing a secure and scalable blockchain platform with a strong developer community. TrueChain hopes to improve upon current platforms with a hybrid consensus protocol called Minerva. This hybrid model will combine a consensus mechanism based on Practical Byzantine Fault Tolerance (pBFT) with a FruitChain-based Proof-of-Work protocol. Fruitchain is designed to minimize the incentives of mining pools by decreasing the variance of mining rewards; making the network more decentralized.
TrueChain's architecture also hopes to improve transaction times and reduce fees, by including a sharding mechanism that is locked to Gas fees. The first use cases for their platform will be digital advertising solutions.
The company is backed by several large Chinese blockchain companies, including ZB.com; one of the largest cryptocurrency exchanges. digital advertising industry

Blockstream is a private, for profit, blockchain technology company, that has played a key role in helping to develop, and fund, many of the key features of the Bitcoin Core platform. Blockstream is focused on developing bitcoin applications and has raised significant funding from several large investment funds. The company also employs several developers that are very influential within the Bitcoin Core development project. This, as well as being of Bitcoin's largest donors, has led to some criticism about conflicts of interest.
Blockstream is developing a number of Bitcoin applications that are intended to encourage adoption and improve transaction times on the bitcoin network. Their primary focus is on Sidechains, which are are extensions to existing blockchains that improve their functionality. The company is also working closely with industry leaders to create the Bitcoin Lightning system that will support higher trading volume and faster transactions on the bitcoin network. Blockstream is also developing a data feed, satellite network, and other applications that they hope will make blockchain more accessible.