Skip to content

Cashu NFC Cards Progress

This page tracks the work behind Flash’s future Cashu NFC card experience.

It is not the Cash Wallet. The Cash Wallet is Flash’s current IBEX USD wallet.


The goal is a privacy-preserving, NFC-based ecash experience that can feel natural for everyday payments, especially where connectivity is poor.

The intended experience is:

  • tap a card
  • move value offline or with weak connectivity when possible
  • keep the payment experience simple for normal users
  • preserve more privacy than a traditional always-online wallet flow

NUT-XX is the working name for the Cashu NFC card protocol work.

At a high level, the protocol work is about:

  • defining how the card stores and spends value
  • making NFC interactions work cleanly with Flash
  • keeping the UX simple enough for merchants and everyday users

The cashu-javacard repo is the JavaCard applet work behind the NFC card.

Current repo signal:

  • JavaCard applet package exists under me.flashapp.cashu
  • the codebase is centered around CashuApplet
  • the repo README describes it as a JavaCard applet implementing the Cashu ecash protocol

This is the low-level card implementation work. It is the piece that makes the NFC card possible.


  • protocol and applet work are in progress
  • the direction is Cashu + NFC + offline-friendly payments
  • this is separate from the Cash Wallet
  • the current Cash Wallet remains the IBEX USD wallet users already see in the app

If done well, Cashu NFC cards could give Flash:

  • better privacy for small payments
  • a more natural tap-to-pay experience
  • less dependence on perfect connectivity
  • a path to offline-friendly merchant payments