Backend systems for money that has to add up.

Malaysia

Online multi-asset broker (FX/CFD and crypto). I work on the crypto trading platform and on payment-provider integrations: Python services (FastAPI, SQLAlchemy, Pydantic) on PostgreSQL and MySQL, with RabbitMQ keeping a client portal and a back office in sync.

• Delivered Apple Pay, Google Pay and Benefit as separate Checkout.com deposit methods for the Bahrain entity; all three are live in production. Wrote the team's end-to-end local testing guide for deposits and refunds.
• Took on 26 backend tickets in my first two months on the crypto platform, across 7 services and shared libraries: back-office API, access-control API, two RabbitMQ consumer services, client-portal API and two shared Python libraries.
• Fixed an HTTP 500 on crypto trades: traced it by correlation id in Grafana/Loki to duplicate asset-pair records, then made symbol resolution deterministic, which also closed the same failure in the market-order and limit-order paths.
• Root-caused a back-office to client-portal KYC sync bug that spanned two RabbitMQ services (the payload was dropped at both the producer and the consumer), reproduced on the exact pinned library versions and confirmed in DEV logs before designing the fix.
• Built paginated, filterable list and CSV/PDF export endpoints with field-level permissions (Casbin) for the maker-checker order-cancellation flow, and extended 8-decimal precision for crypto amounts across APIs, models and ACL definitions.
• Taking on lead-side work as I learn it: splitting stories into backend sub-tasks by layer, sequencing shared-library releases (version, changelog, tags, consumer pins, libraries first), writing deploy order and Notes for QA, and demoing in sprint review.

• Python
• FastAPI
• SQLAlchemy
• Pydantic
• PostgreSQL
• MySQL
• RabbitMQ
• Redis
• Docker
• Kubernetes
• Casbin
• Checkout.com
• Grafana / Loki
• SonarQube

Malaysia

My own side project: a trilingual local-services marketplace for Malaysia, live on the web and Google Play. I built and run the whole stack: a Go API, a Next.js website and a Flutter app for Android and iOS.

• Designed a layered Go API on PostgreSQL with PostGIS: 235 endpoints across 31 domain services and 1,006 test functions, with lint and format gates in CI.
• Built the Next.js website with server-rendered SEO pages in English, Malay and Chinese, and the 48-screen Flutter app, shipped to Google Play and submitted to the App Store.
• Run production on Hetzner with Docker, nginx and Let's Encrypt, isolated staging, encrypted nightly backups to Cloudflare R2, and Sentry and uptime alerts.
• Integrated Firebase push (Android and iOS), Twilio WhatsApp OTP, Google Maps, Google and Apple sign-in, and AI search on the Claude API.

• Go
• PostgreSQL
• PostGIS
• Next.js
• Flutter
• Docker
• Cloudflare R2
• Firebase
• Claude API

Remote

A live proprietary-trading platform: traders buy evaluation challenges, trade on MetaTrader 5, and funded traders take a share of the profit. I owned the MT5 integration and worked across the backend and both dashboards: about 250 commits across five repositories in six months.

• Built the MetaTrader 5 integration service in C#/.NET 7 on MetaQuotes' native Manager API, moving position reads from multi-second network calls to the local pumped cache.
• Designed the real-time breach monitor that checks every active account's loss rules every few seconds from rule snapshots in Redis and fails breached accounts through an idempotent callback.
• Resolved a production data-integrity incident by tracing cross-account figures to the MT5 SDK not being thread-safe: serialised SDK access, locked the connection lifecycle, and added two-source equity checks before any promotion.
• Built end-to-end marketing attribution (first-touch UTM and click IDs, campaign short links, funnel and cohort reports) and rebuilt the React 19 admin dashboard.

• C# / .NET 7
• ASP.NET Core
• MT5 Manager API
• TypeScript
• AdonisJS 5
• MySQL
• Redis
• React 19
• React Query
• AWS

Kuala Lumpur, Malaysia

Payment, ticketing, booking and tourism platforms for enterprise clients in Hong Kong: Java / Spring Boot services with React and Next.js front ends on AWS.

• Built a standalone Octopus payment gateway microservice: multi-tenant, HMAC-SHA256 request signing with replay protection, merchant key rotation and webhook delivery with retries.
• Built Type Approval compliant payment status polling for Ocean Park's ticketing (Octopus over an XML protocol), with idempotent fulfilment and an automatic reconciliation job.
• Built the HKTB AI Trip Planner (~15,000 lines): Next.js 15, AWS Amplify Gen 2, a 5-step questionnaire, drag-and-drop itineraries and an admin portal with DynamoDB batch imports, in 3 languages.
• Shipped the ECHealth booking mini-program end to end in 5 days (React 19 + Spring Boot 3.4, OAuth2 + JWT, AWS SES), fixed an infinite loop firing thousands of API calls per second, and patched 4 CVEs.
• Deployed on AWS (S3, CloudFront, Lambda@Edge, RDS, Cognito, DynamoDB) with Docker and Bitbucket Pipelines; tests with JUnit and Mockito.

• Java 17
• Spring Boot
• Spring Security
• PostgreSQL
• React 19
• Next.js 15
• TypeScript
• AWS
• Docker
• JUnit / Mockito

Remote

Overseas development of AMS (Advanced Marketing System), the platform between Midasbuy payments and game servers that runs gift-package delivery, points and operations dashboards for Tencent's international games.

• Maintained 6 production systems, including the props warehouse, the PaaS interface platform, the points system and the operations portal, in PHP/CodeIgniter, Vue.js and MySQL, with some Go.
• Delivered 31 features and resolved 20 production bugs in the first half of 2025, including a multi-language template system and self-service exports.
• Hourly dashboard patrols across Kubernetes clusters in Grafana and internal tools; incident response by SOP: rollback, scaling, rate limiting and degradation.
• Traced QPS surges with tcpdump to oversized batch reads (20,000+ keys in one mget) and fixed them with request splitting and hot-key isolation; wrote 5-Why post-mortems.

• PHP 8
• CodeIgniter
• Go
• Vue.js
• MySQL / MariaDB
• Kubernetes
• Redis
• Grafana
• Docker

Malaysia

Client projects across PHP/CodeIgniter back ends, Next.js front ends and database tuning.

• Built the Ufootball platform with a 3-person team: a server-rendered Next.js site, a PHP/CodeIgniter API and a back office on MySQL.
• Cut a client ticketing report's SQL from minutes to seconds (about 95% faster) with targeted indexes and query rewrites that removed full table scans.
• Built a multi-language content system (English and Chinese) and Firebase push notifications, and worked directly with clients from requirements to delivery.

• PHP 8
• CodeIgniter
• Next.js
• React
• TypeScript
• MySQL / MariaDB
• Firebase
• Sentry

Kuching, Sarawak

University internship: XML processing, first REST APIs and API testing.

• XML tagging for legal document processing.
• Built basic REST APIs and tested them with Postman.
• Helped build an attendance tracking system.

• XML
• REST APIs
• Postman