x402-cashu

Cashu ecash payment scheme for the x402 protocol. Enables micropayments over HTTP 402 using blind-signed ecash tokens.

Features

• Direct mode -- server verifies and claims Cashu tokens directly against the mint
• No facilitator required -- no chain infrastructure, no gas costs
• Instant settlement -- swap at the mint, no block confirmations
• P2PK support -- optional NUT-10/11 token locking for in-transit security
• Multi-mint -- accept tokens from multiple trusted mints
• Pluggable storage -- bring your own proof storage backend

Install

npm install x402-cashu

Quick Start

Server (Facilitator)

import { ExactCashuFacilitator } from "x402-cashu/facilitator";

const facilitator = new ExactCashuFacilitator({
  mints: ["https://your-trusted-mint.com"],
  unit: "sat",
  // pubkey: "02...",   // optional: require P2PK-locked tokens
  // proofStore: myDB,  // optional: persist claimed proofs
});

// Register with x402 server
server.register("cashu:mainnet", facilitator);

Client

import { ExactCashuClient } from "x402-cashu/client";
import { Wallet } from "@cashu/cashu-ts";

const mintUrl = "https://your-mint.com";
const wallet = new Wallet(mintUrl, { unit: "sat" });
await wallet.loadMint();

const client = new ExactCashuClient(wallet, mintUrl, proofs);
const { payload } = await client.createPaymentPayload(2, paymentRequirements);
// Attach payload.token to X-Payment header

Supported NUTs

| NUT | Name | Status | |-----|------|--------| | 00 | Token format (TokenV4) | Implemented | | 03 | Swap | Implemented | | 07 | Check state | Implemented | | 10 | Spending conditions (P2PK) | Implemented (optional) | | 11 | P2PK signatures | Implemented (optional) | | 05 | Melt | Documented, not yet implemented |

License

Apache-2.0