Open to opportunities

Kristian User

@kristianuser1

Message

Backend developer specializing in scalable APIs, microservices, and performance optimization.

Croatia

Message

What I'm looking for

I seek backend roles focused on scalable APIs, performance optimization, and modernizing legacy systems within collaborative, growth-minded teams.

I am a backend developer with 4+ years building scalable APIs and microservices using Node.js, Express.js, and Nest.js. I focus on reliable authentication, efficient database design, caching, and delivering production-ready systems serving thousands of users.

In my current role I collaborated in a six-member team to replace a legacy application and reworked the company’s largest backend project alongside a senior developer, improving query performance two- to three-fold and implementing Kafka streaming, Redis HSET caching, and WebSocket communication.

I bring hands-on experience across SQL/MySQL, TypeORM/Sequelize, Docker, Redis, Google Cloud, Pub/Sub, Kafka, unit testing, and automation scripting in Python, and I enjoy modernizing legacy codebases and optimizing systems for scale and reliability.

Experience

Work history, roles, and key accomplishments

Current

Backend Developer

Current

Company

Aug 2022 - Present (3 years 2 months)

Developed and maintained microservices and REST APIs using Node.js, Express.js and Nest.js for a production system serving 5k+ users; optimized queries and rewrote legacy backend to improve performance 2–3x and introduced Kafka streaming and Redis HSET caching.

Node Nest TypeORM MySQL Redis Kafka Google Cloud WebSockets

Application Support Engineer

Company

Sep 2021 - Jul 2022 (10 months)

Provided user access management, debugging and backend development in Node.js/TypeScript; built an Express.js API and automation scripts in Python that supported product improvements and led to promotion.