Nguyen Quang Vinh

Backend Engineer

Java Backend Engineer with 3 years across interbank payments, digital signature, and multi-tenant SaaS. I build the service and take it through production releases.

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01Profile

My background is banking and fintech, where duplicates and lost callbacks have a real cost. I also handle production releases and debug the live environment.

3 years: backend engineering
9 projects: banking, fintech, SaaS
2 platforms: released to production
2025 award: Highest Potential Employee

Build: Java 17 & 21, Spring Boot, Spring Security, Spring Cloud, MyBatis, JPA
Connect: REST, Kafka, Toss Payments, Kakao AlimTalk, ISO 20022, HSM (PKCS#11)
Store: PostgreSQL, MySQL, Oracle, SQL Server, Redis
Operate: AWS ECS Fargate, EKS, RDS, S3, CloudFront, Docker, Kubernetes, Helm, GitLab CI, GitHub Actions, Prometheus, Grafana, Linux

02Live demo

Three real flows from S-Space: a normal request, a payment callback that gets lost, and a production release.

Forwarded to the ALB
Routed to a service on ECS Fargate
Query on Multi-AZ RDS
Response returned to the service

Simplified simulation of the S-Space flows. Not live data.

03Case studies

Signature Hub

Centralized digital signing platform

Backend Software Engineer · Team of 4 · banks and enterprises

Built backend services for signing through HSM, remote-signing providers, and VNeID.
Worked on the event-driven signing flow across Spring Boot microservices on Kafka.
Implemented PDF signing and validation (PAdES, PKCS#7) with HSM integration via PKCS#11.

Spring Cloud
Kafka
PostgreSQL

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View architecture

Signature Hub signing flow

ACH Gateway

NAPAS interbank payment gateway

Backend Software Engineer · Team of 12 · banking

Implemented inward-deposit processing on ISO 20022 pacs.008 with validation, business rules, status tracking, and process logging.
Developed reconciliation against NAPAS and Core Banking records to detect mismatches.
Optimized SQL for transaction logs and latest-status lookup.

Spring Boot
SQL Server
Redis

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View architecture

ACH Gateway inward-deposit flow

S-Space

Pilates & fitness studio SaaS

Backend Engineer · Team of 5 · live at s-space.co.kr

Maintained and debugged the production AWS environment: VPC with private subnets, ECS Fargate, Multi-AZ RDS, ALB, CloudFront, S3, and Secrets Manager.
Handled production releases through GitLab CI → ECR → ECS Fargate as main backend maintainer of the auth, user, and center services.
Built a reconciliation job that recovers payments with lost success callbacks and expires stale pending ones.

Java 17
ECS Fargate
RDS MySQL

Read case study

Treat a payment callback as something that can get lost

A success callback is not guaranteed to arrive, so a reconciliation job recovers those payments and expires stale pending ones.

Make data migration re-runnable

Legacy member data moved with scripts that can run again safely, and each run was verified on staging before production.

Watch this flow run

BitBuild

Multi-tenant construction procurement SaaS

Main Backend Engineer · Team of 4 · first sprint to production

Restructured the codebase into a multi-module hexagonal architecture, with ArchUnit tests enforcing boundaries.
Used idempotency keys against duplicate purchase orders and advisory locks for run-once scheduled jobs.
Set up GitLab CI and Docker Compose deployments with health checks.

Java 21
PostgreSQL
Redis

Read case study

View architecture

BitBuild multi-tenant backend

All 9 projects

04Career

04/2026 – Present
Wala-ICT
Backend Software Engineer
Software products for Korean clients. Main backend engineer of a multi-tenant SaaS, responsible for production releases of live platforms.
BitBuild · S-Space · Miribom
11/2024 – 03/2026
Unit Technology Corporation
Backend Software Engineer, R&D
Digital signature and banking solutions. Highest Potential Employee 2025, Most Productive Team 2025.
Signature Hub · Paperless · Easy Doc · ACH Gateway · JCanary Core
09/2023 – 10/2024
Laptrinhjavaweb
Backend Developer
Java backend development.
Java · Spring Boot
08/2025 – Present
Straffico
Freelance Backend Engineer
Project and cost control platform for construction companies. Backend features and the blue-green production release pipeline.
Straffico