Coinkite, the Bitcoin-only hardware wallet manufacturer, recently released the MK5, a significant quality of life and user experience upgrade to the MK4 Coldcard. It builds on the strong security foundations set by its predecessor.
The MK5 comes in many colors and styles. This review covers the Orange and Glow in the Dark versions, as well as their form factor and user experience upgrades. The goal is to answer whether the upgrades are worth the money.
Building on Security Foundations
The MK4 was known for its security platform, which brought two secure element chips from different manufacturers and an MCU to the same device. The MK5 focuses instead on quality of life improvements. It enhances NFC connectivity, reworks the buttons and plastic chassis, and adds a much larger screen. This is the first hardware upgrade to the Coinkite MK line since the launch of the MK4 in 2022. It integrates some technologies that debuted on the Coldcard Q in 2023.
The big upgrades to the user experience are immediately visible. The screen is much larger, perhaps 30% bigger. The announcement blog describes it as a “1.54-inch display protected by Gorilla Glass.” It looks and feels much sturdier than older models.
The next obvious upgrade is the buttons. Unlike the MK4 buttons, which are indented and require your fingers to go into the socket to click, the MK5 buttons are almost level with the chassis. This makes them much easier to press. The press feels good and clicks, giving solid tactile feedback. It is much more comfortable than the unresponsive feel of a touchscreen seen in other hardware wallets.
Design and Chassis Changes
The chassis has been redesigned. The screen section no longer pops out above the keyboard. Instead, it is all one rectangle with comfortable curved edges. It looks more modern and elegant while keeping that cypherpunk transparency that shows off the underlying hardware, a signature design principle of Coinkite products.
The MK5 also comes with a button and screen protector half case that slides and clicks in and out. It can be entirely removed and fits perfectly from the back of the device, exposing the USB power input at the bottom without issue.
NFC Improvements
Coinkite doubles down on NFC support with the MK5. The NFC antenna is increasingly popular in Bitcoin. Examples include NFC tap-to-pay Lightning Bolt cards, Coinkite’s own Tapsigners, and Cashu’s tap-to-send features.
NFC is a powerful alternative to Bluetooth or WiFi. Some hardware wallet providers have adopted these alternatives, but they come with downsides, mainly their range. NFC is short-range by design, working in centimeters. Bluetooth and WiFi work in tens of meters. So the paranoid threat of someone with a long-range antenna connecting to your device remotely vanishes.
There is also no multi-step device connection protocol with NFC. Phones either have the feature on or off, the app starts scanning, and transmission occurs. No pin codes, no sifting through lists of Bluetooth devices. Much simpler user experience in theory. It is also far superior to the SD card transmission of pre-signed transactions. While NFC may technically cross the “airgapped” line in the MK4 and MK5, it still has the best qualities of wireless options. It is set to off by default. Similar to USB connection, the NFC antenna can be severed at a hardware level by scratching off a specific wire.
Coinkite’s NFC Push Tx software is open source and much smaller in terms of lines of code than Bluetooth or WiFi. The full NFC Push Tx code is open source. The client web app side has no license defined and is meant to be integrated by any web application. The hardware side of the code is public but limited by a non-commercial use license.
Collectibles and Packaging
The MK5 comes in a wide range of cases, such as gold-flaked transparent gray, gorgeous orange, and glow in the dark. This review covers the orange and blue glow-in-the-dark versions, though the gold-flaked one might be more interesting. The designs are beautiful, transparent enough to see the hardware, but colorful enough to be stylish.
The packaging was interesting. The box containing the hardware came with a purchase order of items inside tamper-proof security bags. These bags had strong plastic and required a knife to slice through them. They were also marked with a unique number. Inside the bag, another plastic strip contained the same number. When the device was first powered on, it displayed the same number on the screen. This is a flash memory code set per device at the factory. It makes interception and manipulation of the firmware much harder. The next level would be to notify the user of the bag number via email or login so they can verify the number through a side channel.
Integration and Verdict
Integration of NFC Push Tx with mobile wallets was a bit inconsistent. I tried Cove, Bull Bitcoin, and Nunchuck. Of the three, Nunchuck had the best integration, with Cove not far behind. Bull Bitcoin seems to have disabled or hidden the feature. Even with a stronger NFC antenna, I had to remove my phone’s thick case to get reliable data transmission.
As an owner of an MK3, moving to the MK5 is a significant upgrade. At $167 plus shipping, it is a no-brainer for those with older models. For active MK4 users, the bigger screen and better buttons are clear quality-of-life improvements. The better NFC antenna will also make transaction flows smoother. For passive MK4 owners who make a few transactions a year, the upgrades might not be worth it. They still get firmware updates and security benefits.
Disclaimer: Coinkite provided Bitcoin Magazine with a couple of free MK5 Coldcards for testing purposes.
