Java Developer at Global Blue

Ahmad Amirizal Rahmat

Java Developer · Full-Stack Engineer

I build secure, reliable backends with Java and Spring Boot, the kind that move money. 4+ years across banking, insurance, telecom and government, from CIMB's mobile banking to payment tokenization at Global Blue.

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Portrait of Ahmad Amirizal
4+years in industry
6roles since 2021
4industries served
2countries of stakeholders

01 · About

Backend engineer with a full-stack toolkit

I'm a full-stack developer based in Kuala Lumpur, focused on Java and Spring Boot backend engineering, REST API design, and integrating those APIs with React and Angular frontends.

Most of my work sits where reliability matters most: payments, core banking and insurance. I've worked in Scrum squads, run production releases, handled L2 support, and worked directly with stakeholders in Denmark. I also work hands-on with CI/CD pipelines and containerized deployments.

I'm currently completing a BSc (Hons) in Information Technology at MUST alongside full-time work.

  • Now

    Global Blue

    Engineering tokenization and batch payment processing for merchant onboarding.

  • Banking

    CIMB OCTO Mobile App

    Secure Spring Boot microservices for fund transfer and core banking operations.

  • Insurance

    Topdanmark

    Guidewire Policy Center integration across cross-border insurance operations.

02 · Experience

Where I've worked

  1. Feb 2026 – Present

    Java Developer @ Global Blue

    • Own end-to-end development of Spring Boot modules for the merchant onboarding platform, including JWT-based tokenization and verification workflows for every new merchant registration.
    • Architect and drive a Spring Boot batch payment processor for scheduled transaction processing.
    • Drive production deployment and release management, resolving live issues to keep service stable across releases.
    • Java
    • Spring Boot
    • Spring Batch
    • JWT
    • Tokenization
  2. May 2025 – Feb 2026

    Software Developer @ INSCALE Malaysia

    • Aligned requirements directly with stakeholders in Denmark, turning Property and Motor insurance needs into Guidewire Policy Center enhancements with zero disruption to live operations.
    • Built backend modules in GOSU for Guidewire Policy Center and shipped Salesforce frontend features with React and Node.js.
    • Engineered API integrations between Policy Center and external systems, eliminating data inconsistencies.
    • Guidewire
    • GOSU
    • React
    • Node.js
    • Salesforce
  3. Apr 2023 – May 2025

    Software Engineer @ Penril Datability

    • Embedded for 2 years in CIMB's Scrum squad on the Novus Project, delivering core features for the next-generation CIMB OCTO Mobile App.
    • Built secure Spring Boot microservices and REST APIs for fund transfer, foreign transfer, maintenance control and centralized transaction logging, with OAuth2 token validation.
    • Architected an AWS S3-integrated receipt generator that automated receipt storage and retrieval end-to-end.
    • Rebuilt CIMB Back Office Portal workflows in AngularJS and Node.js, and led cross-functional API performance tuning.
    • Spring Boot
    • Microservices
    • OAuth2
    • AWS S3
    • AngularJS
  4. Jul 2022 – Apr 2023

    Java Developer @ Microlink Solutions Berhad

    • Delivered customer management features for Telekom Malaysia's TM Stellar CRM using Java, Spring and SQL.
    • Owned L2 support and production monitoring for CRM batch systems, sustaining SLA compliance.
    • Optimized Spring-based queries and batch jobs to cut processing delays.
    • Java
    • Spring
    • SQL
    • Batch
    • L2 Support
  5. Jan 2022 – Jul 2022

    Programmer Analyst @ Bahagian Pengurusan Hartanah, JPM

    • Built the SISTA (Sistem Pinjaman Peralatan ICT) subsystem end-to-end as a J2EE web app, automating ICT equipment loan requests and approvals.
    • Redesigned a government system interface and led user acceptance testing with stakeholders.
    • J2EE
    • JSP
    • Servlets
    • SQL
  6. Jul 2021 – Dec 2021

    Technician (Internship) @ Mass IT

    • Diagnosed and repaired hardware across 50+ customer PCs and laptops, and explained repairs and upgrades in plain terms.

03 · Projects

Things I've built

Payments infrastructure for Southeast Asia, from a DuitNow-style instant transfer switch to open-source libraries for e-invoicing and payment QR codes, plus the apps merchants and customers use.

Featured · Core · 2026

Instant Transfer Switch

A real-time interbank payment switch in the style of Malaysia's DuitNow. Banks send each other money in seconds, addressed by a phone or IC number, using ISO 20022 messages, and settle what they owe each other once a day. A Go bank simulator plays every bank.

  • Net debit caps: one atomic SQL update, so concurrent transfers can never overshoot
  • Timeouts handled safely: reject after 5 seconds, then camt.056 until the credit is reversed
  • End-of-day settlement with net positions per bank, reconciled by each bank
  • Operations view: Prometheus metrics, a Grafana dashboard and a live switch dashboard
  • Java 21
  • Spring Boot 3.5
  • Go
  • ISO 20022
  • PostgreSQL
  • Testcontainers
  • Prometheus
  • Grafana
View on GitHub
Instant Transfer Switch architecture Alfa BankGo · sender Bravo BankGo · receiver SwitchISO 20022 · caps · settlement PostgreSQL PrometheusGrafana
Open source · 2026

invoisku: MyInvois E-Invoicing Engine

An open-source Java engine for Malaysia's MyInvois (LHDN) e-invoicing. It builds, validates, signs and submits e-invoices, with no dependencies beyond the JDK.

  • XAdES digital signatures over UBL 2.1 JSON, plus a verifier to check them
  • API client that batches within LHDN limits, retries on throttling and stops duplicate submissions
  • Java 17
  • UBL 2.1
  • XAdES
  • RSA-SHA256
  • java.net.http
  • GitHub Actions
GitHub
npm package · 2026

asean-qr: Payment QR Library

A TypeScript library to read, validate and generate the payment QR codes of five countries: DuitNow, PayNow, PromptPay, QRIS and VietQR. Published on npm, with zero dependencies.

  • Reproduces PayNet's published DuitNow examples byte for byte
  • Cross-checked against each country's established library, plus about 10,000 property-based tests per run
  • TypeScript
  • EMVCo
  • Node.js
  • Vitest
  • fast-check
  • npm
npm GitHub
Frontend · 2026

Merchant Dashboard

The React app merchants use to track payments, capture, void and refund them, take card payments through a virtual terminal, and follow their payouts. The live demo simulates the whole gateway in the browser.

  • Idempotent checkout: one key per attempt, so retries never charge twice
  • Card numbers go only to tokenization, never to the payment API
  • React 19
  • TypeScript
  • Tailwind CSS 4
  • TanStack Query
  • MSW
  • Vitest
Live demo GitHub
AI · 2026

Payment Assistant

An AI support assistant that answers merchants' questions, like "why was my payment declined?", from their own live data through tool calling and from the gateway docs through RAG.

  • Runs on Amazon Bedrock (Claude Haiku) or local models via Ollama, one profile switch
  • Read-only tools scoped to the merchant's API key, with per-merchant rate limits
  • Spring AI 1.1
  • Amazon Bedrock
  • Ollama
  • RAG
  • pgvector
  • Java 21
GitHub
Mobile · 2026

Kira: Offline-First Finance App

An Android and iOS app for spending, budgets and recurring bills that works fully offline on SQLite and syncs between devices through a Spring Boot API.

  • Last-write-wins sync with tombstones and a per-user lock, so no edit is lost
  • Budget alerts at 80% and 100%, and reminders before bills are due
  • React Native
  • Expo
  • SQLite
  • Spring Boot
  • PostgreSQL
  • JWT
Download APK GitHub

More on GitHub

Every project here is public on GitHub, with a README on how it works and how to run it.

github.com/amirizalrahmat0799

04 · Skills

Tools I work with

Backend

  • Java
  • Spring Boot
  • Spring Framework
  • Spring Security
  • Hibernate
  • Go
  • RESTful APIs
  • Swagger / OpenAPI
  • Spring Batch
  • Spring AI
  • J2EE
  • Servlet / JSP
  • SLF4J

Security

  • OAuth 2.0
  • OIDC
  • JWT
  • Payment Tokenization
  • Digital Signatures (XAdES)

Frontend

  • React
  • React Native (Expo)
  • Angular
  • TypeScript
  • JavaScript
  • Node.js
  • HTML
  • CSS

Cloud & DevOps

  • AWS
  • Amazon Bedrock
  • Docker
  • Kubernetes
  • Kustomize
  • Prometheus / Grafana
  • Jenkins (JCasC, Job DSL)
  • Docker Compose
  • CI/CD
  • Apache Kafka
  • Maven
  • Gradle
  • Git
  • SonarQube

Databases

  • PostgreSQL
  • Oracle SQL
  • MySQL
  • SQL Server
  • IBM DB2
  • MongoDB
  • SQLite
  • pgvector

Practices

  • Microservices
  • Batch Payment Processing
  • API Integration
  • JUnit, Mockito & Testcontainers
  • ISO 20022
  • Event-Driven Design
  • Offline-First Sync
  • LLM Tool Calling & RAG
  • Agile / Scrum
  • AI-Assisted Development

05 · Education

Education

06 · Contact

Let's build something reliable.

I'm open to conversations about backend and full-stack roles, especially in payments and fintech. References are available on request.

amirizalrahmat@gmail.com +60 19-710 0730

Kuala Lumpur, Malaysia · English & Malay