09/15/2025 updated

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React/Node.js Expert

Florina, Greece Computer Science, University of Peloponneses, BE
Florina, Greece Computer Science, University of Peloponneses, BE

Profile attachments

Resume.pdf

Summary

 Senior MERN Stack Developer with 8+ years of experience in full-stack web development, with a strong focus on JavaScript-based technologies including MongoDB, Express.js, React.js, and Node.js. Skilled in designing and building responsive, scalable applications and complex REST APIs. Excellent communication and teamwork skills, experienced in agile environments and passionate about delivering high-quality software solutions.
 

Technical Skills
  • Frontend: React.js, Redux, Next.js, Vue.js, HTML5, CSS3, Tailwind CSS, Bootstrap, Material UI
  • Backend: Node.js, Express.js, RESTful APIs, Socket.io, JWT Auth
  • 3D & Visualization: WebGL, Three.JS, Pixi.JS, GSAP
  • Database: MongoDB, Mongoose, MySQL, PostgreSQL
  • DevOps & Tools: Git, GitHub, Docker, Jenkins, Nginx, PM2, Vercel, Netlify
  • Testing & Debugging: Jest, Mocha, Cypress, Postman
  • Other: Agile, Scrum, Jira, Figma, REST API, WebSocket, TypeScript

Languages

EnglishFluent

Project history

Lead Full Stack Developer

Kilwar LLC

Internet & IT

< 10 team member

  • Developed and maintained interactive React applications for geospatial data visualization.
  • Built reusable UI components with React, integrated REST APIs with Axios and Redux.
  • Improved performance of data-heavy components, reducing load times by 30%.
  • Implemented end-to-end testing using Cypress.
  • Worked closely with backend and DevOps teams to deploy microservices and enhance system 
  • scalability.

Full Stack Developer

NERDZZ Digitalagentur GmbH

Internet & IT

< 10 team member

- Build Food plan PWA (https://app.tortija.de) using React + Tailwind, Firebase, Node.js/Express.
- Rebuilding iF design website (https://ifdesign.com/) using Gatsby.js and Contentful CMS.
- Build Ecommerce website (https://1apharma.at/) using Next.js, Contentful CMS and Wordpress.
- Built the payment gateway including cardpay, certegy and paypal, etc using Node.js and serverless/terraform, AWS S3 lambda function and dynamoDB, S3 Bucket and SecretManager, etc.
- Develop the shopify application to create very fast the size chart that the users need pre-defined templates using Node.js, Express, Vue.js, Vuex, MySQL, Prisma and Liquid language.

Mobile Flutter Developer

Rio Nord GmbH

Internet & IT

10-50 team member

- Designing and redesigning the screens of the Repeat Native Application.
- Integrate Google Firebase and Google Map API.
- Integrate Restful API.
- Upgrade Native App and React Native Application to Flutter Application.

Certificates

TRIPLEBYTE ENGINEERING CERTIFICATE

TRIPLEBYTE

2022


Portfolio

item-0

Analyzing App

This is the web and mobile application that was built using React, Node.js, Express, MongoDB and AWS Lambda, Serverless, TailwindCSS.
https://my.stakeseeker.com
item-1

Food Plan App

Food plan PWA using React + Tailwind, Firebase, Node.js/Express.
https://app.tortija.de

Recommendations

"I think Sergej is a very smart guy with a lot of know-how and expertise. And that’s why we really enjoy working with him! The results are always what we expect!"

Nerdzz Digitalagentur GmbH

Director (Juliane Foyer)

"If you're looking for a software engineer who you can always count on, look no further. He has a lot of expertise in development, especially React, Node.js and Express. He is not just an excellent software engineer, but has an deep knowledge of the mathematics that should go into software engineering."

Killwar LLC

CTO (Manish Paranjape)


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