Vũ Duy Anh · Software Engineer (Backend & Cloud)

01

A little about me

I work mostly on backend and cloud: lean APIs, well-tuned databases, and solid AWS infrastructure underneath them.

ICPC taught me to think through a problem algorithmically. Real projects taught me to care just as much about stability, security and how a system holds up as it grows.

I like systems that run so quietly nobody has to think about them: clear logs, fast queries, infrastructure you can rebuild with a single command.

At Sotatek I write the APIs and also run AWS infrastructure for clients: CloudFront + WAF in front of S3, CI/CD for Lambda over OIDC, and 9Pay and MoMo payments with backup and restore built in.

2+	Years of hands-on experience
2	AWS certifications
750	TOEIC score

02

Skills & tools

Every tool here has a job in how I build and run systems.

Languages & frameworksAPIs, microservices, data-processing scripts

Node.jsNestJSTypeScriptPythonExpressFastAPI

Dataschema design, query tuning, caching

PostgreSQLMySQLMongoDBRedis

Infrastructure & DevOpsS3, Lambda, Fargate, CloudFront + WAF, CI/CD over OIDC

AWSDockerKubernetesGit

Messaging & APIsbetween services, and with the frontend

REST APIgRPCRabbitMQ

03

Work experience

Four stages, like the life of a butterfly. The current one is shown in full below.

06/2025 — Present

Software Engineer

Sotatek

I design and build backend systems, and advise on and run AWS infrastructure for our clients.

Design, build and tune stable, high-performance RESTful APIs and microservices; model PostgreSQL schemas and optimize the queries that hit them.
Advise on infrastructure: put CloudFront + WAF in front of S3 to rate-limit abuse and speed up file downloads.
Manage client AWS accounts; integrate S3, Lambda, Fargate and a locked-down SFTP server.
Built a standard CI/CD pipeline for Lambda from scratch, authenticating with OIDC instead of long-lived access keys.
Integrated 9Pay and MoMo payments, with backup and restore for transaction data.
Work through requirements with BAs, and with frontend and QC to ship releases that hold up.

Node.jsNestJSPostgreSQLCloudFrontWAFLambdaOIDC9PayMoMo

06/2025 — Present

Software Engineer

Sotatek

I design and build backend systems, and advise on and run AWS infrastructure for our clients.

Design, build and tune stable, high-performance RESTful APIs and microservices; model PostgreSQL schemas and optimize the queries that hit them.
Advise on infrastructure: put CloudFront + WAF in front of S3 to rate-limit abuse and speed up file downloads.
Manage client AWS accounts; integrate S3, Lambda, Fargate and a locked-down SFTP server.
Built a standard CI/CD pipeline for Lambda from scratch, authenticating with OIDC instead of long-lived access keys.
Integrated 9Pay and MoMo payments, with backup and restore for transaction data.
Work through requirements with BAs, and with frontend and QC to ship releases that hold up.

Node.jsNestJSPostgreSQLCloudFrontWAFLambdaOIDC9PayMoMo

04

Selected projects

System architecture, business flows, and what actually came out of them.

2025Backend

Sepolia Health medical platform

Digitizes the whole clinic workflow across web and mobile, with an AI chatbot, StreamChat messaging and Zoom video calls built in.

Next.js · NestJS · Expo · PostgreSQL

3Platforms (web · mobile · API) running on one shared NestJS backend

6Core business areas, from booking and medical records to QR payments

4+Integrated services: Zoom Video, StreamChat, AI chatbot, AWS S3

Read the case study →

2026Backend Developer

StockFlow Cloud inventory system

Inventory management for a multi-branch electronics parts retailer, fully serverless on AWS: a NestJS API on Lambda, Step Functions for imports, and close to zero cost when idle.

NestJS · Lambda · Step Functions · Neon Postgres

0Duplicate records on retry: every staged row carries its own idempotency key and is claimed before stock moves

500 rowsPer stock-write batch, wrapped in one DB transaction: a failure halfway rolls the whole batch back

0Resources billed by the hour: no VPC, NAT, ALB or container, so idle cost is close to zero

Read the case study →

05

Education & certifications

09/2021 — 05/2026

Engineer's degree, Information Technology

Posts and Telecommunications Institute of Technology (PTIT)

2025

PTIT ICPC Finals 2025

International Collegiate Programming Contest (ICPC)

2024

PTIT ICPC Finals 2024 · Honorable Mention

International Collegiate Programming Contest (ICPC)

SAA-C03SAA

AWS Certified Solutions Architect – Associate
05/2026

CLF-C02CCP

AWS Certified Cloud Practitioner
01/2026

TOEIC750

TOEIC 750 · English proficiency
11/2025

I · PTIT ICPC Finals

II · Honorable Mention 2024

The ICPC album: five-hour contests, three people, one computer, a lot of scratch paper. Click the stack to flip through.

§ Engineering Logs

How I think it through

All logs →

Woodcut print of a fairground entrance where a crowd pushes toward one narrow turnstile, a clerk scratches tally marks on a chalkboard, and a messenger runs tally sheets to a counting house.

system-designmysql

100,000 views a second hit one MySQL row

A video goes viral and every viewer runs the same harmless line: views = views + 1. The CPU stays idle and the database still dies. Why one hot row serializes everything, the arithmetic that caps it near 1,000 writes a second, three ways out, and the one place you must never use them.

24 October 2026 · 15 min read

Woodcut print of a 19th-century clinic reception hall: a ledger on the counter, a wall of numbered cubbies, several hands reaching for the same cubby.

system-designpostgresql

Designing a clinic booking system that never double-books

Two patients tap the same 9:30 slot in the same millisecond. Only one of them may win, every time, even at 7 a.m. when a whole city opens the app. Requirements, numbers, schema, four ways to guard the invariant, and what breaks first when traffic spikes.

22 October 2026 · 16 min read