The 21, also known as 21e6, is a Bitcoin corporation founded by Matthew Pauker, and Balaji Srinivasan in 2013. 21 produces the 21 computer: a developer focused Bitcoin mining unit intended to participate in a micro-payments API services economy.
21 operates the BitNodes project, which attempts to data mine the peer to peer Bitcoin network to publish statistics about the overall state of the network.
21 also created and operates the BitcoinFees project, also known as CoinTape, which generates a visualization of unconfirmed transactions and recently confirmed transactions in order to aid transaction fee decision making.
- BitcoinFees: https://bitcoinfees.21.co/
- BitNodes: https://bitnodes.21.co/nodes/
- Website: https://21.co
BitGo is a Bitcoin company founded by Will O'Brien, Mike Belshe, and Ben Davenport that provides a multi-sig web wallet, wallet solutions for Bitcoin companies, and a multi-sig quick deposit service for fast transfers between wallets and exchanges.
BitGo has been operating since 2013, and they raised $12 million dollars in VC funding from Redpoint Ventures in June of 2014.
- Website https://www.bitgo.com/
Bitmain technologies Limited or 比特大陆科技有限公司 is a China based Bitcoin company that has been building and running a large Bitcoin mining operation since early 2013. In addition to offering Bitcoin ASIC mining equipment for sale to third parties under the brand "AntMiner", Bitmain operates its own large mining operations in China under its public mining pool "AntPool".
- Website: https://bitmain.com/
Xapo is a Hong Kong headquartered Bitcoin company run by Argentinian CEO Wences Casares focused on building solutions for mass market consumers to hold and spend Bitcoin. Xapo provides a custodial wallet, and offers a debit card for instant fiat exchange spending.
Xapo raised venture capital funding through various rounds, initially through a Series A investment of twenty million dollars from Benchmark, Fortress Investment Group, Pantera Capital, and Ribbit Capital in March of 2014. Later investments upped the raised total to forty million dollars.
- Website: https://xapo.com/