Skip to content
BUI CHI DUNG
  • AboutSections
  • ExpertiseSections
  • ProjectsSections
  • PrinciplesSections
  • AI EngineeringSections
  • ExperienceSections
  • ContactSections
  • E-Budget case studyCase studies
  • ESG System case studyCase studies
  • AI Sales Forecasting case studyCase studies
  • Digisales case studyCase studies
  • Salesportal case studyCase studies
  • Download CVLinks
  • Send an emailLinks
  • LinkedInLinks

15 results

Software Development Team Leader

BUI CHI DUNG

Backend Engineering, System Design and Technical Leadership

Software Development Team Leader at Excel Technologies building enterprise business systems, with a focus on backend engineering and system design. I care about code quality, testing, maintainability and security.

View projectsGet in touchDownload CVPDF

About

I am a backend-focused Software Engineer with 6+ years of experience building scalable web applications, business systems and API integrations. At Excel Technologies I work as a Software Development Team Leader on enterprise systems, specializing in backend architecture, RBAC, automation workflows, payment and webhook integrations, and RESTful APIs.

In technical decisions I weigh the trade-offs openly and care about code quality, testing, maintainability and security, working with colleagues to deliver systems that support real business operations.

Focus areas

  • Backend Engineering
  • System Design
  • Technical Leadership

Technical expertise

  • Backend

    Backend services for business systems.

    • Node.js
    • NestJS
    • TypeScript
    • Python
    • Django
    • RESTful API
    • RabbitMQ
    • Odoo
    • Bull
    • Passport-JWT
    • CASL
    • ExcelJS
    • Swagger/OpenAPI
    • Firebase
    • Instagram API
    • Web crawling
    • Express
    • GraphQL
    • WebSocket
    • Microservices
    • OAuth2
    • Microsoft SSO
    • Laravel
    • PHP
    • Socket.io
    • gRPC
    • Webhook integrations
    • Payment gateways

  • Database

    Relational and document data stores.

    • PostgreSQL
    • Prisma
    • MongoDB
    • TypeORM
    • Redis
    • Mongoose
    • Migrations
    • Query optimization
    • MySQL
    • SQL Server
    • Elasticsearch
    • Database design
    • ArangoDB

  • Architecture

    The simplest design that meets the requirement.

    • System design
    • Backend architecture
    • Clean Architecture
    • Modular monolith
    • Transactional outbox
    • Queue-based processing
    • RBAC & data scoping
    • ERP integration
    • API design
    • Domain-driven design
    • CQRS
    • Caching strategies
    • Scalability
    • Integration patterns

  • Frontend

    Web interfaces for the systems I build.

    • React.js
    • Next.js
    • JavaScript
    • HTML/CSS
    • Tailwind CSS
    • Redux
    • Vite
    • Responsive design
    • Accessibility

  • Testing / Automation

    Automated checks on the behaviour that matters.

    • Selenium
    • Jest
    • Supertest
    • Vitest
    • Playwright
    • Integration testing
    • Unit testing
    • E2E testing
    • k6 load testing
    • Test strategy

  • Cloud & DevOps

    Containers, cloud services, delivery and observability.

    • Docker
    • Docker Compose
    • Nginx
    • Jenkins
    • AWS (S3, EC2)
    • Cloudflare R2
    • GCP
    • pm2
    • CI/CD
    • Prometheus
    • Grafana
    • Loki
    • Vault

  • AI Integrations

    AI services and workflow automation.

    • OpenAI API
    • Claude API
    • AI Agents
    • Workflow automation

  • Tools

    Day-to-day tooling for collaboration and delivery.

    • Git
    • GitHub
    • GitLab
    • Bitbucket
    • Jira
    • Trello
    • Redmine
    • ClickUp
    • Zeplin
    • Postman

  • Technical leadership

    Technical decisions made with their trade-offs explicit.

    • Technical decisions
    • Trade-off analysis
    • Code quality
    • Collaboration
    • Code review
    • Technical documentation
    • Estimation
    • Mentoring
    • Roadmap planning
    • Cross-team coordination
    • Hiring and interviewing

Featured projects

Filter by technology

  • E-Budget

    Excel Technologies · In progress since February 2026

    A system for managing the corporate group's internal accounting, finance and HR data.

    • 65 domain modules, 130 entities and 488 route handlers (counted from the repository).
    • Streaming Excel export up to 2M rows, measured on a development machine.
    Read the E-Budget architecture case study
    • Node.js 20
    • NestJS
    • TypeScript
    • PostgreSQL
    • TypeORM

  • ESG System

    Excel Technologies · Completed June 2026

    A backend platform for managing ESG data: entering, calculating, approving and reporting sustainability indicators per operating facility and period.

    • 127 route handlers, 26 entities and 22 migrations (counted from the repository).
    • A custom formula engine of about 2,000 lines, built without eval().
    Read the ESG System architecture case study
    • NestJS 10
    • TypeScript
    • PostgreSQL
    • TypeORM
    • Redis

  • AI Sales Forecasting

    Excel Technologies

    A platform where a sales organization reviews AI-generated sales forecasts, adjusts and approves them, and monitors forecast accuracy.

    • A web platform for reviewing, adjusting and approving AI-generated sales forecasts: a Node.js API on PostgreSQL that reads model output from a data warehouse, with a React 19 interface.
    • A cell-level workflow from model volume to submitted, approved or rejected adjustments, a monthly lock calendar and forecast accuracy monitoring.
    • About 22.7k lines of backend and 26k lines of frontend code, 30 route modules and 16 permission keys (counted from the repository).
    Read the AI Sales Forecasting architecture case study
    • Node.js
    • Express
    • PostgreSQL
    • Redshift
    • React
    • TypeScript
    • TanStack

  • Digisales

    Excel Technologies

    The backend of a field sales management app: jobs with a confirmation workflow, recurring task generation, product quality feedback with deadline warnings, and Excel imports.

    • A NestJS backend for a field sales management app: jobs with a confirmation workflow, recurring task generation, product quality feedback with deadline warnings and Excel imports, on PostgreSQL with MongoDB for logs and discussions.
    • Recurring jobs are generated by a scheduled run that chains each occurrence from the previous one, and overdue and due-soon warnings run every minute.
    • About 93.7k lines of TypeScript, 122 entities and 504 route handlers (counted from the repository).
    Read the Digisales architecture case study
    • NestJS
    • TypeScript
    • PostgreSQL
    • TypeORM
    • MongoDB
    • Redis
    • Socket.io

  • Salesportal

    Excel Technologies · December 2024 – May 2025

    Backend for an enterprise sales portal covering orders, customers, pricing, discounts, approvals and notifications, with ERP integration.

    • A modular NestJS monolith on PostgreSQL, MongoDB and Redis, with Bull queues for exchanging data with the ERP system.
    • Role- and permission-based access control, combined with row-level data scoping by sales area and a Redis permission cache.
    • About 700 source files and 107 entities (counted from the repository).
    Read the Salesportal architecture case study
    • NestJS
    • TypeScript
    • PostgreSQL
    • TypeORM
    • MongoDB
    • Redis
    • Bull

  • OpsFlow

    Personal project · in development, foundation stage

    A business operations and approval platform, built as a production-minded engineering exercise. Tooling, the database baseline and the test harness are in place; domain features are not built yet.

    • pnpm monorepo with a Next.js (App Router) web app and a NestJS REST API.
    • PostgreSQL 17 with Prisma 7 migrations, run locally through Docker Compose.
    • Database integration tests that refuse to run unless the target is a local database whose name ends in _test.
    • Next.js
    • NestJS
    • PostgreSQL
    • Prisma
    • Vitest
    • Playwright

Engineering principles

  • Reliability

    Use database constraints and transactions where correctness depends on them, use migrations for every schema change, and never reset data silently.

  • Maintainability

    Prefer simple, explicit designs over speculative abstractions. Keep modules cohesive, dependencies few and conventions consistent.

  • Security

    Validate input at system boundaries, enforce authorization on the server, and keep secrets out of source control, logs and prompts.

  • Trade-offs

    Name what a decision costs. Add infrastructure only when a requirement justifies it, and record why a design was chosen.

AI Engineering & Agentic Workflows

I use AI coding tools inside an engineering workflow. The tools assist; I scope the work, verify the result and approve it.

  1. 01

    Plan & Context

    Scope and decompose the task, and write the context down in project instructions.

    Developer

  2. 02

    Agent-assisted Execution

    The assistant explores, edits and drafts inside that scope. The permission mode stays on ask.

    Agent-assisted

  3. 03

    Review & Verification

    Run tests, lint and type checks, and read the diff for correctness and security.

    Developer

  4. 04

    Human Approval

    Nothing is staged, committed, pushed or deployed without my explicit approval.

    Developer

Stays with the developer

  • Architectural decisions
  • Code quality
  • Security
  • Final acceptance

An engineering workflow, not an autonomous one: a person starts and ends every cycle.

  • AI-assisted coding

    • Used on this portfolioCode exploration, implementation, refactoring and test generation with an AI coding assistant.
    • Stated by meThe same AI-assisted workflow is also applied on the E-Budget project at Excel Technologies.

  • Agentic workflows

    • Configured in this repositoryTask decomposition and context management through written project instructions: stack, principles and workflow.
    • Used on this portfolioRead-only research delegated to sub-agents, with findings checked against the code before use.
    • Configured in this repositoryReview skills are available on request. No hook or other automatic execution is configured.

  • AI integration

    • Listed in my CVOpenAI API and Claude API, AI agents and workflow automation.
    • Listed in my CVIntegration and use of existing tools and services, not building an AI agent platform.

  • Human-in-the-loop

    • Configured in this repositoryPermission mode stays on ask, and read access to environment files is denied.
    • Configured in this repositoryTests target business rules, validation and authorization. A check is never reported as passed unless it ran.
    • Checked by testsCase-study content is guarded against invented metrics, ownership claims and internal details.

Experience

  1. Software Development Team Leader · Excel Technologies

    July 2024 – Present

    • E-Budget (since February 2026): management of the corporate group's internal accounting, finance and HR data.
    • ESG System (February 2026 – June 2026): a backend platform for managing ESG data: entering, calculating, approving and reporting sustainability indicators per operating facility and period.
    • AI Sales Forecasting: a platform for reviewing, adjusting and approving AI-generated sales forecasts, with a monthly lock calendar and forecast accuracy monitoring.
    • Digisales: task management and product quality feedback processing, with recurring tasks generated by scheduled background processes.
    • Salesportal (December 2024 – May 2025): backend of an enterprise sales portal for orders, customers, pricing, discounts and approvals, with ERP integration. Technologies include NestJS, PostgreSQL, MongoDB, Redis and Bull.

  2. Software Engineer · edvin

    March 2022 – March 2024

    • Edvin is a web-based tutoring platform that enhances remote teaching efficiency and engages student learning.
    • Backend solutions with Node.js and Express; databases including ArangoDB, Redis and MySQL.
    • RESTful APIs documented with Swagger and designed with cross-functional teams, plus gRPC for communication between microservices.
    • AWS EC2 and S3 for scalable infrastructure and deployment.
    • Technologies include React.js and Next.js.

  3. Software Engineer · Hybrid Technologies Co., Ltd.

    October 2020 – March 2022

    • Instagram influencer analysis for Spicebox Lab (October 2021 – March 2022): the Instagram Graph API and Basic Display API for Business and Creator account data, and Selenium for scraping and automation of profiles, photos and videos. Tools: Python and Django.
    • Sale Management System (October 2020 – September 2021): developed and maintained an internal Sales Management System for managing project workload, costs and employee resources, using Python and Odoo 13 on PostgreSQL, and took part in code reviews and debugging sessions. Tools also include XML and CSS, JavaScript, RESTful API, Zeplin and Bitbucket.
    • Supported the Spicebox project in analyzing hundreds of influential Instagram users for business and marketing needs.

Education

  • VNUHCM – University of Science

    Bachelor's degree, Computer Science

    2017 – 2021

    Graduated May 2021. Thesis: "Speaker Verification on Embedded System".

Contact

Open to conversations about backend engineering, system design and technical leadership.

chidungface@gmail.com