Coldcard
Bitcoin-only, air-gapped hardware wallet — favoured by cold-storage purists; PSBT via microSD.
| Type | Hardware wallet |
|---|---|
| Custody | Self-custody — the user holds the keys |
| Platforms | Windows, macOS, Linux |
| Open source | Yes — source code |
| Multisig | Yes |
| Account / KYC | No identity verification |
| Official site | coldcard.com |
Cryptocurrencies it holds
Features
Security record
User funds lost through the maker's fault
- 2026 — A firmware bug weakened seed generation: seeds made on affected versions carry about 72 bits of entropy instead of 128, less on the Mk2 and Mk3. Attackers regenerated the keys offline. $115M+ (Galaxy Research); $130M+ (other trackers) · None offered source
No customer-data leak on record as of 13 October 2026.
Seeds made with at least 50 private dice rolls are not affected; every other seed made on an affected version should be moved to a new one.
Only the maker's own failures count; phishing and lab attacks that need the stolen device do not. Every wallet compared: Crypto wallet hacks, and the wallets that were never hacked.
Questions
Has Coldcard been hacked?
Yes. In 2026: A firmware bug weakened seed generation: seeds made on affected versions carry about 72 bits of entropy instead of 128, less on the Mk2 and Mk3. Attackers regenerated the keys offline. Losses: $115M+ (Galaxy Research); $130M+ (other trackers); None offered.
Which coins does Coldcard support?
Bitcoin.
Is Coldcard open source?
Yes. Its source code is public at https://github.com/Coldcard.
Does Coldcard support multisig?
Yes. Coldcard can hold one key of a multi-signature wallet, where several keys on separate devices are needed to move funds — the setup that survives any single wallet failing.
Is Coldcard custodial?
No. Coldcard is self-custody: the user holds the keys, and nobody else can move the funds.
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