Added #

• NowPaymentsClient - Main API client with full endpoint coverage

  • getStatus() - Check API availability
  • getCurrencies() - List all available cryptocurrencies
  • getSelectedCurrencies() - List merchant's enabled currencies
  • getEstimatePrice() - Get price estimates for currency conversion
  • getMinimumPaymentAmount() - Get minimum payment thresholds
  • createPayment() - Create cryptocurrency payments
  • getPaymentStatus() - Check payment status by ID
  • getPayments() - List payments with filtering
  • createInvoice() - Generate payment invoices with URLs
  • authenticate() - JWT authentication for payout operations
  • getBalance() - Check custody account balance
  • createPayout() - Create cryptocurrency payouts
  • verifyPayout() - Verify payouts with 2FA
  • getPayoutStatus() - Check payout status
  • getPayouts() - List payouts with filtering
  • validateAddress() - Validate wallet addresses

• Enums - Type-safe constants (no magic strings)

  • PaymentStatus - waiting, confirming, confirmed, sending, partiallyPaid, finished, failed, refunded, expired
  • PayoutStatus - creating, processing, sending, finished, failed, rejected
  • FiatCurrency - USD, EUR, GBP, and 30+ fiat currencies
  • SortOrder - asc, desc
  • NowPaymentsEnvironment - production, sandbox

• Request Models - Type-safe request builders with toJson()

  • CreatePaymentRequest
  • CreateInvoiceRequest
  • CreatePayoutRequest
  • VerifyPayoutRequest
  • ListPaymentsRequest
  • ListPayoutsRequest
  • EstimatePriceRequest
  • MinimumAmountRequest

• Response Models - Type-safe responses with fromJson() and toJson()

  • PaymentResponse with helper methods (isComplete, isPending, isFailed)
  • PaymentListResponse
  • InvoiceResponse
  • PayoutResponse with helper methods
  • PayoutListResponse
  • ApiStatusResponse
  • CurrenciesResponse
  • EstimatePriceResponse
  • MinimumAmountResponse
  • BalanceResponse
  • AuthResponse

• Exceptions - Typed exception handling

  • NowPaymentsException - Base exception
  • AuthenticationException - 401 errors
  • BadRequestException - 400 errors
  • NotFoundException - 404 errors
  • RateLimitException - 429 errors with retry info
  • RequestFailedException - 402 errors
  • ServerException - 5xx errors

• Utilities

  • IpnValidator - HMAC-SHA512 signature validation for webhooks
  • NowPaymentsConfig - Configuration with environment, timeout, and logging
  • NowPaymentsEndpoints - API endpoint constants

• Features

  • Dependency injection for HTTP client (enables testing)
  • Sandbox and production environment support
  • Optional debug logging
  • Configurable request timeouts
  • Flexible JSON parsing (handles string/number variations from API)