Best DIY and stateless Bitcoin signing devices

I rank only projects you can build today from parts anyone can order. Prices are what the projects and parts sellers list in November 2026. If you would rather buy a finished device, my list of air-gapped wallets you can buy ready-made is the place to start.

SeedSigner is a Raspberry Pi Zero, a small screen hat, and a camera. The project recommends the Pi Zero 1.3 because it has no Wi-Fi or Bluetooth hardware, and the device can only receive data by reading QR codes with its camera. Nothing plugs into your computer. The project puts the cost of parts at usually under $50, and the parts list tells you exactly what to order.

It is stateless: it holds your seed only while it is powered on. You load the seed each session, and the fast way is a SeedQR, a QR code of your seed phrase that SeedSigner helps you transcribe by hand and scans back in a second. It can also create a seed from dice rolls or from camera images.

The release images are reproducible since v0.7.0, so anyone can rebuild them from source and compare. The catch in 2026 is release lag: two security fixes are merged and waiting for the next release. I cover what that means, and how to sign safely in the meantime, in the release-lag section below. It is still my top-rated hardware wallet, and you can read why in my SeedSigner review.

Krux is open-source firmware for off-the-shelf Kendryte K210 devices. Some of those devices come assembled with a case and a touchscreen, so you flash the firmware and you are done: no soldering. The parts page lists eight devices from the $27 to $35 Maix Dock, which you assemble yourself with a rotary encoder or buttons, up to the $58 to $86 WonderMV. Touchscreen boards still on sale are the Yahboom, WonderMV, TZT, and Embed Fire. The Maix Amigo, with the biggest screen, has been discontinued.

Krux talks to your coordinator by QR codes, SD cards, and thermal printers. It can create a seed from the camera, picked words, or D6 or D20 dice rolls, and the project itself recommends dice. You can save an encrypted copy of the seed to the device or an SD card, but its own docs say that storage is meant for convenience only.

Two things changed in 2026. Krux has a new maintainer, Jean Do, whose first release, v26.09.0, fixed a 12-byte buffer overflow in its encryption code that he judged not practically exploitable. The same release notes say Krux is running on discontinued K210 hardware and needs community help to move to new boards. Read my Krux review for the rest.

Specter DIY runs on an STMicroelectronics STM32F469I-DISCO developer board with a 4-inch 800x480 capacitive touchscreen. Add the Waveshare QR scanner to sign by QR code. Without a scanner, you can only use USB or the SD card slot, and USB means it is not air-gapped.

You choose how it handles your seed: agnostic mode forgets all secrets at power-off, and reckless mode stores them in flash. The optional Specter Shield adds a smartcard that encrypts the seed and allows 10 PIN attempts. Its secure bootloader verifies firmware upgrades, so only signed firmware loads after the first install. You install that bootloader yourself, so verify the PGP signatures before you flash.

v1.10.5 rejects dead hardware RNG output and only treats an output as change after checking it against your wallet descriptor. If your board runs v1.9.0 or earlier, install v1.10.3 first, because that release rotated the bootloader signing keys. More in my Specter DIY review.

Every seed starts as a random number. On a factory wallet, you trust the vendor's random number generator and the code around it. In 2026 that trust failed in public: the Coldcard seed flaw sat unnoticed in shipping firmware for years.

Dice take the vendor out of it. SeedSigner and Krux both turn dice rolls into a seed phrase, and SeedSigner documents how to check the result on a separate computer, so you can prove the device did the math honestly.

Wallet companies keep records of who bought a wallet and where they live, and those records leak. In 2026, SafePal exposed order data for about 39,798 customers, Trezor's shipping provider exposed 80,689, and Keystone confirmed a third party took customer shipping information. The full list is on my security incident tracker.

A Raspberry Pi Zero from an electronics store is one hobby board among millions of orders. Nobody can tell from that order that you hold bitcoin.

A stateless signer keeps nothing when it is off. Steal a powered-down SeedSigner and you have a Raspberry Pi. The seed lives only in your backup, and you load it every time you sign.

That is the cost: every session starts with scanning a SeedQR or typing your words. A SeedQR makes it a few seconds, but it also means your seed backup comes out of storage every time you spend. Keep a working SeedQR copy somewhere private and a metal backup somewhere else (see how to back up a seed phrase). Krux and Specter DIY let you store the seed on the device instead, which trades that routine for a device worth stealing.

SeedSigner and Krux have no secure element. Stateless operation covers the obvious attack, since there is no stored seed to extract. The risk that remains is tampering: someone who gets the device or its SD card for an hour could load modified software and hand it back. SeedSigner runs from a microSD card, so verify the signed release image when you flash it and keep the device where you keep your backups.

Specter DIY is the exception here. Its secure bootloader refuses unsigned upgrades, and the Specter Shield adds a smartcard for the seed.

SeedSigner's latest release is 0.8.7 from July 8, 2026. Since then, two security fixes were merged into the development branch: one stops a malicious coordinator from dressing up an attacker's output as your change (merged September 19), and one verifies input amounts before showing the fee (merged October 20). Neither is in a release as of November 5, 2026.

Until the next release ships:

A DIY project depends on boards someone else manufactures. The K210 chip under every Krux device is discontinued, in the maintainer's own words, and the Maix Amigo is no longer for sale. Boards built on the chip are still sold today, so buy a spare while you can.

If you build anything here, buy two boards. A second one costs little, and it lets you restore your seed on identical hardware if the first one dies after its board goes out of stock.

SeedSigner says there are no "official" or "approved" SeedSigner vendors. Its site lists kit sellers, including one run by the project's creator, and says sellers should never ship devices with preloaded software. A kit is convenient, but buying it puts your name on a Bitcoin hardware seller's customer list, which is the exact list DIY lets you avoid.

My advice: order the board, screen, and camera from general electronics stores, and flash the software yourself from the project's own release page. If you do buy a kit, wipe the SD card and flash a fresh, verified image before you create a seed.

Jade's firmware is open source, and Blockstream's repository includes a DIY guide for running it on consumer boards. It lists boards such as the LilyGO T-Display at about $10, the M5Stack M5StickS3 at about $16, and camera boards such as the ESP32-CAM ($10 to $20) and LilyGO T-Camera Plus ($30 to $50). I have not rated a DIY Jade, so it sits outside the ranking.

Read the caveats before you build. The guide warns in capital letters not to flash DIY firmware onto an official Jade or official firmware onto DIY hardware. Secure Boot is optional, and enabling it cannot be undone. These boards use the ESP32, a Wi-Fi and Bluetooth chip, so the radio is on the board. The popular community guide at bitcoin-tools/diyjade skips Secure Boot, has no camera support, and pins an old firmware version, while official Jade tags are at 1.0.41. Follow Blockstream's own guide and build the current version.

A DIY signer makes a strong second or third key in a multisig, because it shares no hardware, firmware, or supply chain with the factory wallets next to it. Specter DIY was built for this: its main focus is multisig with other hardware wallets. SeedSigner verifies single-sig and multisig change outputs, with the release-lag caveat above.

Build the wallet in a coordinator such as Sparrow, back up the descriptor with each seed, and keep each key in a different place. My 2-of-3 multisig guide walks through it, and my multisig coordinator rankings show which apps work with which devices.

Built a SeedSigner and want a single-sig wallet? You are done. Back up the seed on metal and stop there.