Nikolai Rybalkin - Principal Engineer (Contract)

Q: Where is Nikolai based?

Nikolai is based in Teningen, Germany .

Q: What languages does Nikolai speak?

Nikolai speaks the following languages: Russian (Native), English (Advanced), German (Elementary) .

Q: How many years of experience does Nikolai have?

Nikolai has at least 13 years of experience. During this time, Nikolai has worked in at least 5 different roles and for 5 different companies . The average length of individual experience is 3 years and 8 months . Note that Nikolai may not have shared all experience and actually has more experience.

Q: What is Nikolai's latest experience?

Nikolai's most recent position is Principal Engineer (Contract) at Independent Contractor .

Q: What companies has Nikolai worked for in recent years?

In recent years, Nikolai has worked for Independent Contractor and Auditdata .

Q: Which industries is Nikolai most experienced in?

Nikolai is most experienced in industries like Information Technology , Healthcare , and Banking and Finance . Nikolai also has some experience in Transportation .

Q: Which business areas is Nikolai most experienced in?

Nikolai is most experienced in business areas like Information Technology , Product Development , and Supply Chain Management .

Q: Which industries has Nikolai worked in recently?

Nikolai has recently worked in industries like Healthcare , Banking and Finance , and Information Technology .

Q: Which business areas has Nikolai worked in recently?

Nikolai has recently worked in business areas like Information Technology , Product Development , and Supply Chain Management .

Recommended expert

Teningen, Germany

Experience

Sep 2025 - Present

8 months

Germany

Principal Engineer (Contract)

Independent Contractor

Built multi-tenant warehouse management SaaS: 40 API modules, 150+ routes, real-time updates via SignalR
Technologies: React, TypeScript, Redux Toolkit, RTK Query, Webpack, .NET 8, PostgreSQL, SignalR, Docker, GitHub Actions
Landing: Next.js 14, Tailwind CSS, 17 localizations, Stripe payments (SEPA + cards)
Testing: xUnit (150+ files), Jest, Playwright E2E; CI/CD: Docker, GitHub Actions
Telegram AI agent: daily inventory reports, shipment alerts and warehouse monitoring delivered to mobile
Background jobs and scheduled tasks for automated reporting, alerts, and data synchronization
Built German e-invoicing SaaS (XRechnung, ZUGFeRD), GDPR compliant, multi-tenant architecture
Technologies: React, TypeScript, RTK Query, Python, FastAPI, PostgreSQL, Redis, Celery; Testing: pytest (294 tests), Playwright
Implemented async task queues (Celery + Redis) and scheduled jobs for invoice processing, email notifications, and DATEV export
Developed AI-powered content automation platform: analyzes Git commits, generates and publishes posts to LinkedIn and Discord, responds to GitHub Issues automatically
Cron-based automated publishing pipeline and scheduled content generation and distribution across platforms
Multi-LLM architecture (OpenAI, Claude, Gemini) with pluggable provider system and RAG-based knowledge assistant integrated across all SaaS products

Mar 2019 - Sep 2025

6 years 7 months

Senior Full Stack Engineer

Auditdata

Designed micro-frontend architecture (Module Federation) adopted across product teams, reducing integration conflicts by 80%
Built React component library: 50+ components with Storybook documentation, reducing UI development time by 50%
Co-initiated and built React Native apps (iOS + Windows) outside main roadmap; apps now in production and generating revenue
Delivered critical modules under tight deadlines, taking ownership of the most complex frontend challenges
Reduced bundle sizes by approximately 40% and improved page load performance
Modernized legacy modules into maintainable React/TypeScript codebase with 90% test coverage
Acted as unofficial tech lead: owned most complex features from design to delivery
Mentored junior developers and led architectural discussions with lead architect and product owner
Core architectural patterns designed became foundation for system-wide refactoring

Apr 2018 - Mar 2019

1 year

Kyiv, Ukraine

Javascript Engineer

NewGround LLC (Evolution Gaming)

Built high-performance UIs using React, TypeScript, and Redux for live streaming environments
Developed modular components with Jest and Enzyme test coverage
Optimized Webpack builds to improve load times and animation performance

Jun 2016 - Apr 2018

1 year 11 months

Kyiv, Ukraine

Frontend Software Engineer

KaaIoT (CyberVision)

Built front-end architecture using React, Angular 4, Redux, and TypeScript for IoT platform
Developed reusable UI components for a scalable, maintainable codebase

Jan 2013 - May 2016

3 years 5 months

Kyiv, Ukraine

Frontend Developer

Frontmen Agency, Innovecs

Developed responsive websites and web applications using HTML, CSS, JavaScript, and jQuery
Built CMS-based projects with WordPress and Drupal
Implemented UI components and client-facing features for multiple commercial projects

Industry Experience

See where this freelancer has spent most of their professional time.

Experienced in Information Technology, Healthcare, Banking and Finance, and Transportation.

Information Technology

Healthcare

Banking and Finance

Transportation

Business Area Experience

See which departments and functions this freelancer has contributed to most.

Experienced in Information Technology, Product Development, and Supply Chain Management.

Information Technology

Product Development

Supply Chain Management

Summary

Senior React / Full Stack Engineer with 13+ years building enterprise web applications. EU work authorization — no visa sponsorship required. Expertise in React, Next.js, TypeScript, Node.js, and .NET. Deep background in micro-frontend architecture, cloud deployment (Azure, AWS), CI/CD, and high-performance UI systems. Agile, Scrum, TDD.

Skills

Frontend:

React
Next.js
Redux
Redux Toolkit
Rtk Query
Typescript
Javascript
Html5
Css3
Tailwind Css
Material Ui
Storybook
Jest
React Testing Library
Playwright
Webpack
Vite

Backend:

Node.js
Express.js
Python
Fastapi
C#
.Net 8
Asp.net Core
Entity Framework Core
Rest Apis
Graphql
Websockets
Signalr

Cloud & Devops:

Microsoft Azure
Aws (S3, Ec2, Cloudfront)
Azure Devops
Github Actions
Ci/cd Pipelines
Docker
Nginx
Sentry

Mobile:

React Native (Ios, Android, Windows)

Databases:

Postgresql
Azure Sql
Mysql
Mongodb
Redis

Architecture:

Micro-frontends
Module Federation
Microservices
Multi-tenant Systems
Vertical Slices
Component Libraries
Design Systems
Accessibility (Wcag 2.1, A11y, Aria)
Agile
Scrum
Kanban
Tdd
System Design

Ai/llm:

Openai Api
Claude (Anthropic)
Gemini
Multi-llm Architecture
Prompt Engineering
Dynamic Prompt Generation
Rag
Ai Agents
Telegram Bot Integration
Llm-powered Workflow Automation

Languages

Russian

Native

English

Advanced

German

Elementary

Education

Oct 2010 - Jun 2014

Belgorod State University

Bachelor of Engineering · Engineering · Belgorod, Russian Federation

Oct 2002 - Jun 2005

Maikop State Technological University

Specialist Degree · Maykop, Russian Federation

Statistics

Experience

Total positions 5

Experience in Information Technology 7 y

Avg length 2 y 8 m

Longest experience 6 y 6 m

Global Experience

Countries worked in 2 (Ukraine, Germany)

Primary country Ukraine

Expertise

Recent roles Principal Engineer (Contract), Senior Full Stack Engineer, Javascript Engineer

Main industries Information Technology, Healthcare, Banking and Finance

Main business areas Information Technology, Product Development, Supply Chain Management

Qualifications

Highest degree Bachelor

Profile

Created

April 2026

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Frequently asked questions

Do you have questions? Here you can find further information.

Where is Nikolai based?

Nikolai is based in Teningen, Germany.

What languages does Nikolai speak?

Nikolai speaks the following languages: Russian (Native), English (Advanced), German (Elementary).

How many years of experience does Nikolai have?

Nikolai has at least 13 years of experience. During this time, Nikolai has worked in at least 5 different roles and for 5 different companies. The average length of individual experience is 3 years and 8 months. Note that Nikolai may not have shared all experience and actually has more experience.

What roles would Nikolai be best suited for?

Based on recent experience, Nikolai would be well-suited for roles such as: Principal Engineer (Contract), Senior Full Stack Engineer, Javascript Engineer.

What is Nikolai's latest experience?

Nikolai's most recent position is Principal Engineer (Contract) at Independent Contractor.

What companies has Nikolai worked for in recent years?

In recent years, Nikolai has worked for Independent Contractor and Auditdata.

Which industries is Nikolai most experienced in?

Nikolai is most experienced in industries like Information Technology, Healthcare, and Banking and Finance. Nikolai also has some experience in Transportation.

Which business areas is Nikolai most experienced in?

Nikolai is most experienced in business areas like Information Technology, Product Development, and Supply Chain Management.

Which industries has Nikolai worked in recently?

Nikolai has recently worked in industries like Healthcare, Banking and Finance, and Information Technology.

Which business areas has Nikolai worked in recently?

Nikolai has recently worked in business areas like Information Technology, Product Development, and Supply Chain Management.

What is Nikolai's education?

Nikolai holds a Bachelor in Engineering from Belgorod State University.

What is the availability of Nikolai?

Nikolai is immediately available for suitable projects.

What is the rate of Nikolai?

Nikolai's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.