Open Source · BIP32/BIP39 · AES-256

DIY Hardware
Crypto Wallet
on $3 chip.

Air-gapped signing device built on ESP32. Private keys never leave the hardware. Same architecture as Ledger — fully open source.

$3
Hardware Cost
AES-256
Encryption
0
Wireless Radios
🔑
BIP39 Mnemonic
12-word seed, 128-bit entropy. Compatible with MetaMask, Ledger.
🔐
AES-256 Encrypted Storage
Seed bound to chip eFuse MAC. Flash dump = useless ciphertext.
📵
WiFi + BT Permanently Off
Disabled at boot via ESP32 API. Zero radio exposure.
🖐
Physical Confirmation
Every transaction requires pressing OK on the hardware button.
Get Started
01
Plug your ESP32 Vault into USB
02
Click Connect Device in the nav bar
03
Select the COM / tty port from the dialog
04
Enter your PIN on the device buttons
↗ GitHub

* Requires Chrome or Edge — Web Serial API

Don't have a device?
→
Get an ESP32 DevKit (~$2 on AliExpress)
→
Get an SH1106 OLED 128×64 (~$2)
→
Get 3 push buttons (~$0.30)
→
Flash firmware via PlatformIO
→
Full wiring + setup in README
📖 Read Docs
🔑
Wallet Not Set Up
Connected to device but no wallet found. Run the Python companion to generate your seed.

python companion.py --port COM6

Choose option 1 (Setup wallet), write down your 12 words, then set a PIN on the device buttons. Come back and reconnect.
ETH Balance
— ETH
BTC Balance
— BTC
Device Status
Connection
ONLINE
Wireless
DISABLED ✓
Encryption
AES-256
Ethereum Address
Fetching...
Etherscan ↗
Bitcoin Address
Fetching...
Blockchain ↗
Send ETH
Saved Addresses
Terminal
Send ETH
How it works
01
App builds the transaction from your inputs
02
TX hash sent to ESP32 over USB serial
03
Device shows details on OLED display
04
Press OK button on device to sign
05
App broadcasts signed TX to Ethereum
✓ Private key never transmitted
✓ You physically approve every TX
Saved Addresses
Up to 5 stored on device
No saved addresses. Add one below.
Serial Monitor
ADDR_ETH
ADDR_BTC
LISTADDR
SEND_WORDS
⚡
Confirm Transaction
Review details carefully before signing
To
—
Amount
—
Network
Ethereum Mainnet
⚠ Check your ESP32 OLED screen and press the physical OK button to sign. Press UP to reject.