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Zbigniew User

@zbigniewuser

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Senior .NET engineer building business-critical cloud and product platforms.

Poland

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What I'm looking for

I’m looking for a senior .NET/cloud product engineering role where I can build reliable backend platforms, microfrontend-ready UIs, and practical automation—collaborating closely with product teams to modernize and ship real business outcomes.

I’m a Senior Software Engineer focused on building business-critical applications—from backend platforms to microfrontend solutions and end-to-end product delivery. I combine hands-on engineering with product thinking and pragmatic problem solving to deliver reliable software that supports real business processes.

Recently, I worked on a stablecoin payment platform (Payoneer by Ciklum), delivering microfrontend modernization across both frontend and backend. I designed backend functionality, test plans, and automated tests, using AI-assisted development tools like Cursor and GitHub Copilot to accelerate delivery and improve development efficiency.

I also lead product execution as a founder/solo full-stack developer (Firu.pl), designing and building the full marketplace architecture—listings, search, booking flow, user accounts, and payments. Earlier at Bytes by Ciklum, I served as Dev Lead / Senior .NET Engineer, migrating legacy UI into a new application, optimizing SQL queries, and contributing across .NET and Go services in cloud and CI/CD-driven environments.

Across prior roles, I developed microfrontend-based data processing capabilities (RSM International by Ciklum), integrating Azure Data Factory workflows and OCR/data extraction modules. I’ve also built technology demonstrators in LGSVL/SVL Simulator and owned full product development as a sole developer (Flotilo.pl), including integrations, infrastructure, and serverless auto-scaling deployments.

Experience

Work history, roles, and key accomplishments

Current

Expert .NET Developer

Current

Payoneer by Ciklum

Dec 2025 - Present (7 months)

Delivered new features and modernization improvements for a microfrontend-based application, working across frontend and backend. Implemented backend functionality and automated tests, using AI-assisted tools like Cursor and GitHub Copilot to improve delivery efficiency.

.NET React SQL MongoDB Kafka AWS Azure Automated Testing Cursor GitHub Copilot

Current

Founder / Solo Full-Stack

Current

Firu.pl

Oct 2025 - Present (9 months)

Designed and implemented the full architecture for a peer-to-peer rental marketplace, including listings, search, booking flow, user accounts, and payments. Led the product from idea to a working marketplace, covering both technical development and business execution.

Next.js PostgreSQL Marketplace Development

Current

Solo Full-Stack Developer

Current

Flotilo.pl

Dec 2019 - Present (6 years 7 months)

Owned full product development as the sole developer, delivering backend services, frontend features, infrastructure, and integrations for a bidding platform. Built integrations with Pipedrive CRM, classified ads portals, Firebase, and analytics tools, and implemented a serverless auto-scaling architecture for low-maintenance production deployment.

Flutter Firebase Pipedrive Serverless Architecture

Dev Lead / Senior .NET Engineer

Bytes by Ciklum

Sep 2024 - Dec 2025 (1 year 3 months)

Migrated selected UI components from a legacy platform to a new application to support modernization and faster development. Built and improved application views, optimized SQL queries, and contributed backend development across .NET and Go services.

.NET 8+C#Azure Docker Temporal PostgreSQL Elasticsearch Next.js React Shadcn Ui Tailwind CI CD SQL Query Optimization Go

.NET Backend Developer

RSM International by Ciklum

Jan 2022 - Jun 2024 (2 years 5 months)

Developed frontend and backend features for a microfrontend-based data processing platform, including React UI modules and .NET services. Integrated Azure Data Factory workflows with OCR/data extraction modules to improve automation and delivery quality.

.NET SQL React Azure Azure Data Factory Document Intelligence

Senior Software Developer

LG Electronics by Luxoft

Jan 2021 - Aug 2022 (1 year 7 months)

Built technology demonstrators and proof-of-concept scenarios in LGSVL/SVL Simulator to showcase autonomous driving and smart infrastructure applications. Developed vision-based scenarios, integrated simulator logic and environment setup, and coordinated interactions between vehicles, sensors, infrastructure, and backend services.

LGSVL SVL Simulator Autonomous Driving Vision Based Scenarios Camera Assisted Parking Sensor Integration

C# Unity 3D Software Developer

Fuero Games

Oct 2012 - Jan 2021 (8 years 3 months)

Released and maintained multiple online/mobile game projects using C# with Unity 3D and related backend technologies. Contributed to networking migrations, AI-driven testing systems, scalable real-time multiplayer infrastructure, and VR/AR/WebGL prototypes, including ongoing server maintenance.