Why the split - KEYCARD and KEYCARD SHELL - instead of one device?
Conventional hardware wallets put keys, screen, keypad and firmware in one sealed unit. That's simpler, and it has three consequences we wanted to avoid:
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The device is the secret. Lose it or break it and you're in recovery, racing whoever found it. With us, the key material lives on a €25 card you can hold several of. The expensive part holds nothing.
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Backups are awkward. Most wallets back up to 24 words written on paper - which is then the weakest thing in your setup, and the thing most people actually lose crypto to. Here, backup is another Keycard, initialised from the same seed. Same EAL6+ protection as the original, not a piece of paper in a drawer. Put one in a safe, one with family, one in a deposit box. Redundancy costs €25, not a compromise in security model.
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Multiple wallets need multiple devices. One Shell reads any number of Keycards. Cold storage on one card, daily spending on another, a shared household wallet on a third - one reader, hard separation between them. Not accounts inside one seed, but genuinely independent keys on separate hardware.
And because the keys aren't in the Shell, the Shell being open-source and inspectable matters more, not less - you can verify exactly what the thing displaying your transactions is doing, and it's the same code for everyone.
Full stack: https://github.com/keycard-tech/keycard-shell
Posted Aug 3, 2026, 2:33 AM UTC