Seed phrase

A seed phrase is the human-readable backup of your wallet’s private key — a string of ordinary words you write down when you set up a self-custodial wallet. Type those words into a fresh wallet and your funds reappear; that’s the recovery part.

Why it matters: with a self-custodial card, the seed phrase is your money. Lose it and there’s no support line that can reset it — the funds are unreachable. Leak it — a photo in your camera roll, a “support agent” who asks for it, a phishing page — and anyone can drain the wallet from anywhere. So the single most important job of self-custody isn’t picking the right card, it’s keeping that phrase offline, written down, and never typed into anything but your own wallet. No legitimate app or person will ever ask you for it.

For example: cards like ether.fi Cash and Gnosis Pay spend from a Safe smart account you control, so the recovery phrase behind your signing wallet guards the whole balance. That’s the flip side of a custodial card such as Coinbase, where the company holds the keys and a forgotten password is just a reset away — convenient, but it means they can also freeze you out.