Senior Fullstack Engineer • Warsaw, Poland

Building modern web products from interface to infrastructure.

I’m Khanh Hoang Tran, a Full-Stack Developer with 5 years of experience building web applications. I take ownership of features from requirements and technical planning through implementation, testing, code review, and deployment.

Frontend•Backend•Databases•Cloud & DevOps•Production Ready

View Selected WorkContact Me LinkedIn

khariton.aaa.97@gmail.comWarsaw, Poland

Portrait of Khanh Hoang Tran — Khanh Hoang TranWarsaw, Poland

Experience5 YearsWeb application development

FrontendReactNext.js & TypeScript

BackendNestJSNode.js & Express

DataSQLPostgreSQL & Prisma

EducationVIZJAComputer Science, 2021–2025

Based inWarsawPoland · Europe/Warsaw

01 // Executive Profile

About Me

A dedicated fullstack engineer focused on end-to-end reliability, architectural precision, and practical product execution.

Khanh Hoang Tran

Warsaw, Poland • Fullstack Developer

I am a full-stack developer with 5 years of experience building web applications. My work spans education and publishing platforms, a SaaS product for coaches and trainers, a B2B CRM, and appointment scheduling.

I take ownership of selected features from requirements and technical planning through implementation, testing, code review, and deployment. I connect React interfaces to APIs, build NestJS services, and work with PostgreSQL and Prisma.

My experience includes teams in Germany, Bulgaria, and the USA. I work with teammates to clarify requirements, plan features, share progress, and demonstrate completed changes.

TypeScript across frontend and backend

PostgreSQL & Prisma data modeling

Docker & automated CI/CD

English B1–B2 · Polish B2

System Architecture

Designing the connections between Next.js interfaces, NestJS APIs, and PostgreSQL data models.

Product-Minded Delivery

Delivering booking flows, CRM features, content interfaces, and presentation tools around user requirements.

Team Collaboration

Collaborating with teams, sharing progress, clarifying requirements, and demonstrating completed changes.

Code Quality & Security

Validating API inputs, checking workspace permissions, testing booking conflicts, and automating builds.

02 // Technical Capabilities

Technology Stack

Technologies from my CV, grouped by the work they support.

Frontend

React · Next.js · TypeScript

React / Redux
Next.js
JavaScript ES6+
TypeScript
Zustand
TanStack Query
Tailwind CSS
Shadcn/UI
Bootstrap

Backend & APIs

Services and integrations

Node.js
NestJS
Express.js
WebSockets
Socket.io
Stripe
Apollo GraphQL
PHP / Symfony
Twig

Databases & ORM

Persistence and data access

PostgreSQL
MySQL
MongoDB
DynamoDB
Prisma
TypeORM
Drizzle ORM

Cloud & Messaging

Infrastructure and background work

AWS
GCP
Azure
Redis
RabbitMQ
BullMQ
SNS / SQS

Testing & DevOps

Verification and delivery

Jest
Vitest
Playwright
Docker
Nginx
GitHub Actions
GitLab
Webpack

AI & Workflow

Tools and product integrations

Claude Code
Cursor
Codex
Agentic AI development
Gemini API
Python
Jira

03 // End-to-End Methodology

From UI to Production

From requirements to implementation, testing, and deployment — the way I take ownership of a feature.

PHASE 01

Requirements & Planning

Clarify requirements with the team, plan selected features, and agree on implementation details.

Feature ownershipTeam planning

PHASE 02

Frontend & User Flows

Build React components and Next.js interfaces for booking, CRM, publishing, and content creation.

ReactNext.js

PHASE 03

Backend & Integration

Build NestJS endpoints, validate inputs, connect REST APIs, and integrate external services.

NestJSREST APIs

PHASE 04

Data & Consistency

Model time slots and bookings, use Prisma for database access, and handle conflicting bookings in a single transaction.

PostgreSQLPrisma

PHASE 05

Testing & Permissions

Test booking flows and concurrent requests. Check permissions and ensure records stay isolated across workspaces.

Integration testsWorkspace isolation

PHASE 06

Build & Delivery

Use Docker and CI/CD workflows to automate builds and run tests before releases.

DockerGitHub Actions

04 // Commercial History

Professional Experience

Experience across education, publishing, SaaS, CRM, and scheduling products.

Senior Fullstack Engineer

2025–2026

LimeByte GmbH · Germany

ingacademy.de & hospitalityinside.com

Maintained and improved an education portal for engineers and a publishing platform for the hospitality industry.
Updated pages and components in the existing Next.js Pages Router application.
Upgraded libraries and plugins, adapted integrations, and fixed compatibility issues.
Owned frontend improvements and bug fixes from investigation through implementation and verification.

Next.js
NestJS
Node.js
TypeScript
Webpack
Docker
Python
GitLab
Codex

Senior Fullstack Engineer

2025–2026

Enterpreno.eu · Germany, Bulgaria

Yourflip — SaaS for coaches and trainers

Contributed to migrating the backend from PHP/Symfony to NestJS and connected React components to REST APIs.
Integrated the Gemini API for image generation and a Python-based handwriting-to-font project.
Built React features for presentations and arranging visual content for printing.
Integrated reusable React components into Twig-rendered Symfony pages; planned, implemented, and tested selected features.

React
NestJS
PHP
Symfony
Twig
PostgreSQL
Apollo GraphQL
Playwright
Docker
Python

Senior Fullstack Engineer

2024–2025

Bramberlane CRM · Germany

B2B CRM for small service businesses

Built customer forms and lists with search filters and pagination.
Implemented live chat in customer records so staff could message customers directly from the CRM.
Validated API inputs and checked permissions within each workspace.
Included workspace IDs in Redis cache keys and tested isolation of customer records.
Owned selected CRM features from planning through implementation and testing.

Next.js
NestJS
TypeScript
PostgreSQL
Prisma
Redis
Socket.io
AWS S3
AWS

Mid-Level Full-Stack Engineer

2022–2024

Tervelane Scheduling · USA

Appointment booking for tutors and consultants

Designed the Next.js, NestJS, and PostgreSQL architecture and the data model for time slots and bookings.
Built availability endpoints, input validation, Prisma database access, and the Next.js booking flow.
Fixed double booking by reserving a slot and creating the booking in one database transaction.
Added integration tests, including concurrent requests for the same slot, and CI/CD workflows to build and test releases.

Next.js
NestJS
TypeScript
PostgreSQL
Prisma
AWS
GitHub

Feature Ownership

Practical disciplines shaped by the products I have worked on.

Reusable Interfaces

React components integrated into existing applications, including Symfony and Twig pages.

Reliable Booking

Atomic database transactions and integration tests for concurrent booking requests.

Workspace Isolation

API permission checks, workspace-specific Redis keys, and isolation tests.

Product Integrations

Gemini image generation and Python-based handwriting-to-font tools.

Continuous Delivery

Automated builds and test workflows before releases.

Engineering Focus

Core development disciplines I champion across every codebase, system design, and pull request.

Clean Architecture

Decoupled layers, modular NestJS providers, and domain separation.

Reliability

Reusable Components

Atomic UI systems with strict TypeScript prop contracts.

Maintainability

Performance (CWV)

Sub-second LCP, minimal CLS, dynamic imports, and asset optimization.

Optimization

Robust API Design

Strict DTO schema validation, OpenAPI / Swagger documentation.

Interoperability

Auth & Security

Role-based access control, AWS Cognito, signed JWTs, and CSRF protection.

Security

Real-Time Messaging

Bi-directional WebSockets and Socket.IO channel management.

Real-Time

DB Performance

PostgreSQL indexing, query optimization, and Prisma connection pooling.

Database

Cloud Infrastructure

AWS S3 storage pipelines, IAM policies, and cloud networking.

Cloud

Developer Experience

Prettier, ESLint, Git hooks, and zero-friction onboarding docs.

Productivity

Continuous CI/CD

Automated testing suites, Docker builds, and zero-downtime deployment.

DevOps

06 // Selected Projects

Production Systems & Case Studies

Selected commercial work and a personal portfolio project.

Featured work · Dec 2024 – Present

SaaS

Yourflip

Enterpreno.net

A SaaS platform that helps coaches and trainers create presentations and prepare visual materials for printing.

React
NestJS
Node.js
Symfony
PostgreSQL
Python
Gemini API

Visit Yourflip ↗

yourflip · engineering work

My contributions

Contributed to migrating the backend from PHP/Symfony to NestJS.
Integrated the Gemini API so users could generate images from text prompts directly in the app.
Connected a Python-based handwriting tool that turns writing samples into custom fonts.
Built and improved React features for creating presentations and arranging print layouts.
Gradually replaced parts of the Twig-based frontend with reusable React components connected to REST APIs.
Owned image and font generation features from technical planning through implementation and testing.
Collaborated with the team on feature planning and reviews, using Jira to track tasks, communicate progress, and coordinate delivery.
Improved frontend performance with a focus on responsive presentation editing and efficient, reusable React components.

Dec 2024 – Present

SaaS

hospitalityinside.com

LimeByte GmbH

A publishing platform and weekly online trade magazine for the international hotel industry, available in German and English.

My contributions

Maintained and improved pages and components in the existing Next.js Pages Router application.
Upgraded third-party libraries and plugins, adapted integrations, and resolved update-related regressions.
Took frontend improvements and bug fixes from investigation through implementation and verification.
Worked with the team to plan improvements, track fixes in Jira, share progress, and demonstrate completed changes.
Refined frontend performance and page responsiveness, treating optimization as part of ongoing maintenance.

Next.js
Node.js
TypeScript
Webpack
Docker

Visit project ↗

Dec 2024 – Present

Education Platform

ingacademy.de

LimeByte GmbH

A continuing education portal where engineers can find courses, seminars, and degree programs from universities and other education providers.

My contributions

Maintained and improved the frontend of an education portal for engineers.
Updated existing integrations and fixed compatibility issues following library and plugin upgrades.
Owned frontend improvements from investigating issues through implementing and verifying changes.
Collaborated with the team on feature planning, tracked implementation tasks in Jira, and demonstrated completed work.
Improved frontend performance and responsiveness, with attention to efficient page rendering and component behavior.

Next.js
NestJS
TypeScript
Webpack
Docker

Visit project ↗

Feb 2024 – Jan 2025

B2B · CRM

Bramberlane

A B2B CRM for small service businesses to manage customer records, search client lists, and control access within separate workspaces.

My contributions

Built customer forms and lists with search filters and pagination.
Implemented live chat in customer records so staff could message customers directly from the CRM.
Validated API inputs and checked user permissions within each workspace.
Scoped Redis cache keys by workspace ID and tested that customer records remained isolated between workspaces.
Owned selected CRM features from planning through implementation and testing, coordinating requirements and progress with the team through Jira and regular demos.
Focused on efficient customer-list loading and responsive search, filtering, and pagination, alongside workspace-scoped Redis caching.

Next.js
NestJS
TypeScript
PostgreSQL
Prisma
Redis
Socket.io
AWS S3
AWS

Oct 2021 – Nov 2024

B2B · Scheduling

Tervelane Scheduling

An appointment booking platform for tutors and consultants, with client-facing time-slot selection and provider availability management.

My contributions

Designed the Next.js, NestJS, and PostgreSQL architecture and the data model for time slots and bookings.
Built availability and booking endpoints with input validation and database access through Prisma.
Implemented the Next.js booking flow, including selecting another slot when the requested time was no longer available.
Fixed a double-booking bug by reserving the slot and creating the booking in a single database transaction.
Added integration tests for the booking flow, including concurrent requests for the same slot.
Set up CI/CD workflows to automate builds and run tests before releases.
Worked with the team to clarify booking rules and coordinate feature delivery, using Jira to track tasks, issues, and progress.
Refined booking-flow performance with a focus on responsive availability checks and efficient API and database interactions.