@x402/core

Framework-agnostic core utilities for x402 protocol on Solana.

Installation

npm install @x402/core

Quick Start

import { PaymentVerifier, createErrorResponse } from '@x402/core';

const verifier = new PaymentVerifier({
  facilitatorUrl: 'http://localhost:3001'
});

const result = await verifier.verify(paymentRequest);
if (result.verified) {
  // Payment is valid
} else {
  return createErrorResponse(result.error, 'PAYMENT_FAILED');
}

Features

• ✅ Payment verification with facilitator integration
• ✅ Ed25519 signature validation
• ✅ Nonce-based replay protection
• ✅ SOL/Lamports conversion utilities
• ✅ Payment request serialization
• ✅ TypeScript support

API Reference

PaymentVerifier

class PaymentVerifier {
  constructor(config: { facilitatorUrl: string });
  verify(paymentRequest: any): Promise<{ verified: boolean; error?: string }>;
  verifyFromHeader(headerValue: string): Promise<{ verified: boolean; error?: string }>;
  checkHealth(): Promise<{ status: string }>;
}

Utility Functions

// Response helpers
createErrorResponse(error: string, code?: string)
createSuccessResponse<T>(data: T)

// Payment processing
parsePaymentHeader(headerValue: string)
createPaymentHeader(paymentRequest: any)
validatePaymentRequest(paymentRequest: any, options?: any)

// Amount conversion
solToLamports(sol: number): string
lamportsToSol(lamports: string | number): number

License

MIT © ENVXX Team