Coldcard Mk4

Editorial assessment

The Coldcard MK4 is Coinkite's compact Bitcoin-only device in USB stick format with documented air-gapped, PSBT and microSD workflow. It is aimed at users who only sign Bitcoin and prefer isolation via SD card or NFC. Multi-chain and Bluetooth are not the profile of this device; the larger Coldcard Q remains the keyboard variant of the same line with more control surface.

Readable firmware code under a Commons Clause licence is documented. Two secure elements are a manufacturer claim; no formal CC or FIPS certification is listed. NFC complements USB. There is no built-in battery, and the screen is small and monochrome. The air-gapped path does not require a permanently connected computer. Desktop and mobile platforms are documented. SLIP39 is absent. PSBT and microSD paths require compatible wallet software rather than a simple cable-and-app workflow.

In a hardware wallet comparison, the MK4 is typically above USB entry-level devices such as the Nano S Plus and below touch air gap devices - the exact RRP values are in the purchase characteristics. This is not an assessment that Bitcoin-only is safer, but rather a classification of the Coinkite workflow and its compact form factor in the lower air-gap segment.

Compared to the Coldcard Q, the MK4 remains the compact stick without a keyboard form factor and without a device battery; opposite the BitBox02 Multi EVM chains are missing, but the documented air gap path is added.

In Direct comparison BitBox02 Bitcoin-only vs Coldcard Mk4 The form factor, connection and backup of the two hardware wallets are directly opposite - the basis for an objective comparison without an overall grade.

Specs, chains and price proximity are in the characteristics table - this text only classifies.