Krux

Krux adapts to several supported devices rather than requiring one enclosure. Some arrive assembled; development-board kits may need soldering. Start with the parts list for the exact model, including its screen and camera. The firmware is open source and free to download, while the hardware is a separate purchase. The project describes itself as research and development software, which is a relevant limit for anyone expecting a finished consumer wallet.

The release guide explains how to check both the download's checksum and its signature before installation. The flashing command depends on the device family, so selecting an approximately similar board is not enough. Installing the firmware uses a computer connection; subsequent signing can exchange data optically.

A coordinator such as Sparrow manages the online side of the wallet. In Krux, export the Extended Public Key as a QR code and scan it into the coordinator. Compare the wallet settings shown on both devices. For multiple signers, also load and preserve the wallet descriptor, which records how the keys form the wallet. Address checks can then confirm that a receive address belongs to that configuration.

To authorize a payment, prepare it in the coordinator and display its transaction QR. On Krux, choose Sign, then PSBT, then Load from camera. PSBT is the unsigned or partially signed transaction file. Inspect its details before selecting Sign to QR code, then scan the result back into the coordinator for broadcast. An SD card is another transfer option.

No hosted Krux account is part of this local signing process. Recovery still depends on your seed backup and, where applicable, the wallet descriptor; the screen and firmware do not replace those records.