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April 2024 — July 2025 · Singapore

Multiplier

Lead Software Engineer

Led the design and development of global payment infrastructure enabling $30M+ in payouts across 110+ countries, while architecting the Billing & Metering Engine for 2,000+ enterprise customers.

Team6 SDEs
Duration1.3 years
Stack
TypeScriptNode.jsPostgreSQLKafka
DomainGlobal Payments / HR Tech
Projects

What I built here

01

Global Payment Service

Designed and built a global payment service enabling $30M+ in payouts across 110+ countries, integrating with multiple banks and payment providers for employees, contractors, and freelancers.

Challenge

Payouts needed to work across 110+ countries with different banking systems, currencies, holidays, and regulatory requirements — while hitting payout date accuracy targets.

Approach

Multi-provider integration with intelligent routing based on SLAs, FX rates, and local bank/holiday calendars. Built fallback chains and real-time payout tracking.

Impact

Achieved 96% payout date accuracy across all 110+ countries. Enabled $30M+ in total payouts to employees, contractors, and freelancers globally.

02

Direct Debit Infrastructure

Led implementation of direct debit capabilities across 4 major currencies via ACH (USA), SEPA (Europe), eGIRO (Singapore), and credit cards.

Challenge

Manual invoice collection was slow and unreliable. Different regions have completely different direct debit standards and compliance requirements.

Approach

Built unified direct debit abstraction over ACH, SEPA, eGIRO, and card rails. Auto-debit scheduling with retry logic and compliance-aware mandate management.

Impact

95% of invoice payments processed within due dates for auto-debit customers. Significantly accelerated fund collection across all regions.

03

Billing & Metering Engine

Primary architect for the billing and metering engine automating client invoicing based on contract numbers, payouts processed, and value-added service utilization.

Challenge

Manual invoicing for 2,000+ enterprise customers was error-prone, slow, and lacked transparency for billing disputes.

Approach

Event-driven metering pipeline that tracks usage in real-time, automated invoice generation tied to contracts, and a dispute resolution workflow.

Impact

Automated accurate billing for 2,000+ enterprise customers. Transparent billing reduced disputes and improved collection efficiency.

Architecture

System design highlights

Payout Request
Provider Router
Bank / PSP
Reconciliation

Key decisions

  • Intelligent provider routing optimizing for SLAs, FX rates, and local calendars
  • Unified direct debit abstraction over 4 regional payment rails
  • Event-driven metering for real-time usage tracking and automated invoicing
  • Fallback chains across providers for payout reliability

Trade-offs accepted

  • Multi-provider complexity for better reliability and coverage across 110+ countries
  • Eventual consistency in metering — acceptable for billing cycles, not real-time balances
  • Per-region compliance logic adds maintenance cost but is non-negotiable for financial services