Block.io

Block.io was a hosted multi-signature cryptocurrency wallet service operated by Atriark Corp, a Canadian company that ran the platform from 2014 onward. The service supported Bitcoin, Litecoin, and Dogecoin and was structured as both a consumer-facing wallet and a Wallet-as-a-Service product that developers integrated through a REST API. Businesses building Bitcoin payment flows, faucets, casinos, or marketplace settlement could provision wallets and address streams for their users without running their own node infrastructure or implementing key management from scratch.

The wallet used a 2-of-3 multi-signature key model that split signing authority between three parties: a server key held by Block.io, a user key encrypted with a personal password, and a backup key issued to the user as a recovery secret. This design meant that a Block.io server compromise alone could not move user funds, since the second signature required the user-encrypted key, and lost passwords could be recovered through the backup key. Two-factor authentication was supported through TOTP and backup codes, and the API exposed standard transaction primitives including sendto, receive, balance, and notification webhooks for incoming transfers.

The block.io domain stopped responding in December 2024 and now redirects to chain.so, Atriark’s blockchain explorer product that had run alongside the wallet service. The Wallet-as-a-Service offering was wound down and the consumer wallet interface is no longer accessible. Existing users who held funds before shutdown would have needed to use the platform’s withdrawal flow to move funds to a self-custodial wallet. No new features or updates have been announced since the shutdown.