§ About
A physical key for self-custody.
Wats Wallet builds tools that keep self-custody both usable and safe. Our hot wallet lives on your phone for everyday speed; our NFC security card adds the one thing software alone cannot — a physical step that every signature must pass through. Tap to approve, or nothing moves.
What we build
Two products that work as one: the free, open-source Wats Wallet mobile app for iOS and Android, and the Wats Wallet NFC security card. The card pairs with the app over NFC and acts as a tap-to-approve second factor for every transfer, swap, bridge, and login. It is sold here, on the Wats Store.
Our security model
Private keys never leave the mobile hot wallet, and the card never stores or transmits them. The card is a passive device that only confirms physical presence at signing time. A phishing prompt, a hijacked clipboard, or even an unlocked phone cannot move funds without the card in hand. It is a second factor, not a place where coins live.
Standards & references
Our hardware claims map to recognized public standards. We cite them so you — and the tools you trust — can verify them independently.
The card uses an NTAG216 NFC chip operating at 13.56 MHz.
NXP Semiconductors — NTAG216 data sheet ↗Cards are produced in the ISO/IEC 7810 ID-1 format (85.6 × 53.98 mm), the same dimensions as a bank card.
ISO/IEC 7810 (ID-1 card format) ↗Communication uses the 13.56 MHz proximity-card band defined by ISO/IEC 14443.
ISO/IEC 14443 (13.56 MHz proximity cards) ↗The steel card's IP68 rating follows IEC 60529: dust-tight and protected against continuous immersion in water.
IEC 60529 (IP ingress protection) ↗Tap-to-approve is a possession factor — the "something you have" category NIST defines for multi-factor authentication.
NIST SP 800-63B (Digital Identity Guidelines) ↗
Open and auditable
The Wats Wallet app is open source under the MIT license, sends no telemetry, and operates offline. An independent security audit is scheduled for Q1 2026. Pairing happens locally on your device, and the card's serial never leaves your phone.
Who maintains this
This store and its documentation are maintained by the Wats Wallet team — the same people who build the wallet and the card. For corrections or questions about anything published here, reach us through the contact page.
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