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Tomasz Antosiak

@tomaszantosiak

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.NET BACKEND DEVELOPER | LEGACY SYSTEM MODERNIZATION | CI/CD & CLEAN ARCHITECTURE

Poland

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What I'm looking for

I’m looking for a remote backend-focused role where I can contribute to meaningful products, take ownership of architecture and performance, and work in a team that values clean code, long-term thinking, and autonomy. I'm especially interested in modernizing complex systems and working with .NET, SQL, Docker, and CI/CD pipelines.

.NET Backend Developer with 10+ years of experience designing, modernizing, and maintaining large-scale backend systems with .NET, C#, MS SQL, and EF Core. Skilled in clean architecture, CI/CD pipelines, and DevOps practices. Effective at mentoring teams, aligning business and technical goals, and delivering results in remote, autonomous environments.

Experience

Work history, roles, and key accomplishments

Senior .NET Developer

Knowit

Jun 2024 - Jun 2025 (1 year)

Platform modernization – Swedish public sector (Pulsen Group). Migration from .NET Framework 4.7.2 to .NET 8.
- EF model recreation – Database First, 100+ SQL tables
- Legacy frontend refactor – UX, code cleanup
- Patient visit modules – web and mobile, consistent UX
- Multi-source data integration – normalized business logic
- Scrum collaboration – cross-functional team, architectural input

Backend Developer -> Technical Lead

Caspio

Jul 2020 - Mar 2024 (3 years 8 months)

Low-code SaaS platform development and leadership.
- Customer-specific backend services
- Code review leadership – mentoring, backlog grooming, knowledge sharing
- Sprint planning – estimation, scoping, stakeholder alignment
- Technical liaison
- Business-to-tech translation – clarity of scope and delivery
- Fostered team cohesion and motivation – improved collaboration and ownership culture

Software Developer

Aon

Nov 2018 - Jun 2020 (1 year 7 months)

Insurance web apps – standalone and server-generated frontend.
- AngularJS quoting app – client-only, GDPR-compliant
- Server-side rendering engine – .NET Core, dynamic HTML
- Full-cycle delivery – development, debugging, testing, and QA support

Senior Software Engineer

Motorola Solutions Poland

Dec 2016 - Oct 2018 (1 year 10 months)

CI/CD and DevOps for 100+ developer environment.
- CI/CD pipeline automation – Jenkins, TFS, reporting, InstallShield, and Artifactory
- Dev support – build troubleshooting and documentation
- Infrastructure improvements – small DevOps team leadership
- Security scanning – Nessus, SonarQube, and Dotfuscator
- System monitoring – error log tracking and reporting

Developer

CENTRUM Holding 1 Spółka Akcyjna SP.K

Jun 2014 - Nov 2016 (2 years 5 months)

Dealer management system – automotive sales, service, and finance.
- Price list automation – SSIS, scheduled tasks, and brand-specific updates
- Inventory module enhancement – PZ, PW, WZ, RW, and MM documents
- Finance module development – tax logic, cost reporting, and cash flow reporting
- Legacy maintenance – VB.NET and C#, with a focus on technical debt reduction

Junior Developer

LogicSynergy

Jul 2013 - May 2014 (10 months)

ERP for water utilities – desktop and mobile systems.
- Financial module support – billing, accounting, and reporting workflows
- Mobile app for PSION – Windows CE, C++, and SQLite
- Data sync improvements – mobile-to-desktop database integration