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Payment Microservice - Airwallex

Backend microservice and custom TypeScript SDK powering Airwallex payment integrations.

  • Node.js
  • Express.js
  • TypeScript
  • MySQL
  • MongoDB
  • Sequelize
  • Redis
  • SQS
  • Axios
  • Slack
  • Sentry
  • Jest

Node.js microservice for Airwallex payment integration, serving as the backend for both the admin and merchant platforms across Singapore and Australia. I built the internal TypeScript SDK, SQS-based webhook processing system, auth layer, bank beneficiary integration, and platform account management - all from scratch.

Highlights

  1. Built a versioned internal TypeScript SDK for the Airwallex REST API (v2025-11-11) - Airwallex has no stable Node.js SDK. Covers platform accounts, connected accounts, payment intents, beneficiaries, hosted flows, RFIs, and terminal devices with full type definitions and a single controlled import surface.
  2. Designed the SDK auth system: proactive token refresh with a 2-minute lookahead, concurrent request deduplication via a shared login promise (no duplicate auth calls under load), automatic 401 retry with cache invalidation, and a pluggable TokenCache interface for future Redis-backed implementations.
  3. Built the SQS-based webhook processing system - 10 domain queues covering payments, payouts, onboarding, capabilities, disputes, fund splits, refunds, and terminal events. Long-poll listeners with backoff, dual persistence (MySQL for structured data, MongoDB for raw webhook payloads), and per-event DLQ retry.
  4. Implemented a real-time Slack notification system with two separate alert channels: infrastructure errors (SQS exceptions, DB failures, unhandled errors with full stack traces) and business events (account activation, suspension with reason codes, RFI action-required alerts).
  5. Built the full bank integration (beneficiary management) - create, update, delete, and set-default for payout bank accounts, scoped per connected account with masked account number handling in API responses.
  6. Built platform account and connected account management - full lifecycle including KYC/KYB submission, suspend and reactivate flows, payment capability tracking per method (Visa, Mastercard, Apple Pay, and more) with audit history, and webhook-driven status transitions stored with full history.

Last updated: 2026-06-06