Coldcard
Bitcoin-only hardware security ecosystem with air-gapped signing devices, physical bearer instruments, and NFC cards
Why We Recommend Coldcard
Coinkite has established itself as a trusted name in Bitcoin security through its rigorous hardware architecture. COLDCARD wallets employ dual secure elements from different manufacturers (Microchip ATECC608 and Maxim DS28C36B) plus a main microcontroller, splitting secrets so an attacker would need to compromise all three chips simultaneously to access funds. The BIP39 seed is encrypted with AES-256-CTR derived from secrets across both secure elements and the MCU, protected by PIN-gated access with limited login attempts and anti-phishing words to prevent brute force attacks and device substitution.
The firmware is fully open-source and auditable, with secure boot ensuring only Coinkite-signed updates can run. Air-gapped operation means COLDCARD devices never need to connect to a networked computer—transactions are signed offline using microSD cards or QR codes (on the Q model). This Bitcoin-only focus deliberately avoids altcoin support, dramatically reducing the attack surface compared to multi-coin wallets. The company maintains a strong reputation within the cypherpunk and Bitcoin security community, with years of operation from Canada and widespread adoption among serious self-custody practitioners.
Best For
COLDCARD is ideal for Bitcoin holders who prioritize security above convenience and want the highest-assurance cold storage available. If you're holding significant amounts for the long term and want true air-gapped signing with no USB connection required, COLDCARD's microSD and QR-based workflows deliver that peace of mind. The Bitcoin-only design appeals to those who see multi-coin support as unnecessary attack surface and prefer hardware engineered exclusively for one purpose.
Power users and developers will appreciate advanced features like multisig coordination, PSBT workflows, HSM mode via CKBunker for automated signing scenarios, and dice-based entropy generation for paranoid seed creation. These tools integrate seamlessly with software wallets like Sparrow and Nunchuk, making COLDCARD a cornerstone of sophisticated self-custody setups.
OPENDIME, SATSCARD, and TAPSIGNER serve different audiences: merchants and event organizers who want physical Bitcoin for promotions or gifts, artists embedding value into physical works, and anyone wanting to hand someone Bitcoin like cash. BLOCKCLOCK products appeal to enthusiasts wanting ambient Bitcoin data displays, while SEEDPLATE and security accessories round out a complete self-custody toolkit.
Services & Features
- COLDCARD Q air-gapped wallet ~$249
- COLDCARD Mk4 signing device ~$158
- OPENDIME bearer sticks ~$70/3-pack
- TAPSIGNER NFC signing cards
- SATSCARD physical Bitcoin cards
- SATSCHIP NFC art embeddings
- BLOCKCLOCK mini/micro displays
- SEEDPLATE steel backup plates
- COLDPOWER USB isolator
- CKBunker HSM software
Considerations
Bitcoin-only by design with no altcoin support whatsoever. Advanced features like multisig, PSBT workflows, and HSM mode have a steeper learning curve than consumer-friendly alternatives. International buyers should account for shipping costs, customs duties, and potential import restrictions.
