Open to opportunities

Hau Nguyen User

@haunguyenuser

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Full-stack developer building maintainable web, mobile, and API-first products for SaaS.

Vietnam

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What I'm looking for

I’m looking for full-stack roles where I own features end-to-end—from UI behavior through API design, database queries, tests, and QA—building reliable SaaS, CRM, and marketplace workflows with maintainable code.

I’m a full-stack developer with 6+ years building web, mobile, and backend systems end-to-end—from UI behavior through API design, database queries, tests, and release checks. I enjoy keeping products reliable and maintainable while shipping features that real teams can use.

My recent work spans React/Next.js and Vue/Nuxt interfaces, plus Node.js and Python APIs. I’ve focused on payment and identity integrations and on product workflows backed by PostgreSQL and MongoDB.

I’m strongest in full-stack ownership with product teams: turning client conversations into buildable slices, designing the UI/API/data path, writing tests, and guiding features through QA. I also partner across product, design, frontend, backend, and client teams on flows like booking, invoicing, and admin dashboards.

I’m comfortable using AI-assisted development to speed up prototyping, refactoring, and test drafting while keeping human review in the loop. From Flygplatsbolaget to OhMyOppa and several freelance SaaS projects, I’ve consistently improved delivery readiness, performance, and reliability.

Experience

Work history, roles, and key accomplishments

Current

Full-stack Developer

Current

Wsoft Pro

Nov 2025 - Present (8 months)

Built SaaS booking, agreement, admin, and invoicing features across React screens, ExpressJS APIs, and MongoDB collections for airport reservation management. Reduced repeated booking, customer, and invoice lookups by ~30% through caching and tighter API payloads, and turned requirements into smaller booking tasks with edge-case reviews.

TypeScript ReactJS ExpressJS MongoDB Tanstack Query Zustand Jest React Testing Library Supertest

Full-stack Developer

Napa Global

Jan 2026 - May 2026 (4 months)

Developed a mobile platform connecting tourists with Korean tour guides, including booking, payments, real-time chat, and reviews using React Native and NestJS APIs. Integrated Firebase Auth and payments (PayPal/Stripe/Toss/Paddle) and cut repeated booking/chat API requests by ~33% during QA using typed API contracts, mobile caching, and secure token handling.

TypeScript React Native ReactJS NestJS PostgreSQL AWS Tanstack Query Zustand Jest React Testing Library Supertest PayPal Stripe Toss Paddle I18next

Full-stack Developer

Pureative

Jun 2025 - Oct 2025 (4 months)

Built apartment rental management features including rental screens, NestJS services, and PostgreSQL models for apartments, tenants, and admin tasks. Improved dashboard performance by ~30% and reduced repeated rental form work by moving shared UI patterns into reusable components.

TypeScript ReactJS NestJS PostgreSQL Redux toolkit Jest React Testing Library Supertest

Full-stack Developer

TextureStudio

Dec 2024 - Sep 2025 (9 months)

Built VueJS/NuxtJS interfaces backed by FastAPI and PostgreSQL for an asset platform serving real-product texture catalogs, 3D model listings, HDRI assets, and brand portfolio metadata. Improved browsing across thousands of assets with SSR, lazy loading, database-aware filters, and indexed metadata, reducing repeated texture queries by ~40%.

TypeScript fastAPI PostgreSQL GCP Redux toolkit Vitest Supertest

Full-stack Developer

RefereeHub

Oct 2024 - Feb 2025 (4 months)

Developed VueJS/NuxtJS booking screens backed by FastAPI and PostgreSQL for referee availability, match requests, and assignments. Added booking validation and responsive UI states, reduced duplicate referee assignment cases by ~33% during QA, and supported GCP deployment checks and production runtime fixes.

TypeScript fastAPI PostgreSQL GCP Redux toolkit Vitest Supertest

Front-end Developer

Pureative

Feb 2023 - Aug 2023 (6 months)

Built NextJS/TypeScript pages for customers comparing home EV charger options, aligned with a WordPress-backed content model. Reduced initial page payload by ~30% and improved first-load rendering consistency using optimized media, typed components, and cleaner headless CMS fetches.

TypeScript WordPress Redux toolkit Jest React Testing Library

Back-end Developer

Pureative

Jul 2022 - Jun 2023 (11 months)

Developed FastAPI services for prompt-improvement workflows backed by MongoDB for a mobile application that helps users improve ChatGPT prompts. Integrated OpenAI API into the mobile flow and reduced prompt-improvement response times by ~50% during integration testing while lowering validation retries with clearer request schemas and modular FastAPI services.

TypeScript fastAPI OpenAI API MongoDB Flutter GraphQL Pytest

Full-stack Developer

G-Signal

Feb 2020 - Oct 2021 (1 year 8 months)

Developed and led CRM feature work for managing interactions with current and potential customers across ReactJS screens, NestJS services, PostgreSQL models, and AntDesign components. Improved reliability by indexing queries and refining state APIs to reduce stale row reads during QA and lower nightly import failures, and supported clients in defining and troubleshooting CRM workflows.