Multisig

Multisig is short for multi-signature: a wallet that won’t release funds until a set number of approvals sign off — two of three keys, say, rather than one key controlling everything. It’s the difference between one person holding the only key to the vault and needing a quorum to open it.

Why it matters: a plain wallet has a single point of failure. Steal that one key and the money’s gone. Multisig spreads that risk: you can require a second approver, a recovery signer, or a daily limit, so one compromised device or phished signature doesn’t hand over everything. That’s what lets a self-custodial card hold your funds without being fragile — the rules live on-chain, where the issuer can’t quietly rewrite them. The trade-off is a little more setup and a little gas to operate.

For example: the ether.fi Cash card gives each user a Safe — ether.fi’s own help center says the Safe “combines the security of multisig technology” and that only you can authorise transactions according to your account’s signature rules. Gnosis Pay builds on the same Safe smart account machinery. In both cases the card can only move money when your account signs, which is the whole point of multisig.