Physical Bitcoin vouchers where no single party knows the private key at issuance time.

A sender and recipient share a physical card. The issuer generates a random secret (K_x) and prints it as a barcode inside the card. The sender chooses a two-word passphrase (K_a) and writes it on the back. Neither half alone can derive the private key — only the recipient holding both can claim the funds.

See SPEC.md for the full cryptographic specification.

How it works

Create — sender generates a batch of vouchers in the browser. Argon2id combines K_x + K_a to derive a Taproot address. Only the address and K_x are sent to the server; K_a never leaves the browser.
Print — download a PDF: one sheet of QR codes (addresses, for funding), one sheet of barcodes (K_x values, for the inside of the card).
Fund — sender sends Bitcoin to each address and writes the two-word passphrase on the back of the matching card.
Claim — recipient scans the barcode, enters the two words, and sweeps the funds to their own wallet. Entirely client-side.

Repository structure

packages/core        # Framework-agnostic crypto library (K_x gen, Argon2id, BIP32, P2TR)
apps/server          # Express 5 API + PDF generation + static file serving
apps/client          # Vite + React SPA (create, batch status, claim flows)

Development

Requires Node 24 and pnpm.

pnpm install
pnpm start        # builds everything, then starts the server at http://localhost:3000

Deployment

The app is packaged as a Docker image. SQLite data lives at /data — mount a persistent volume there.

docker build -t orange-ticket .
docker run -p 3000:3000 -v /your/data:/data orange-ticket

For Dokku:

dokku apps:create orange-ticket
dokku storage:mount orange-ticket /var/lib/dokku/data/storage/orange-ticket:/data
git push dokku main

License

MIT — see LICENSE.