Jobs at VSI Warsaw

Senior Full Stack Developer (Integrations & Middleware)

A high-level Senior Full Stack Developer who thrives on the "logic" side of engineering. While you’ll work across the stack, your primary mission is to build, secure, and maintain the complex web of integrations connecting our core business systems.

You are the go-to expert for C#, APIs, and Middleware. While this is an individual contributor role, you will play a vital part in levelling up the team, identifying knowledge gaps in our junior developers (particularly in backend logic and security) and coaching them through code reviews and collaborative builds.

Please submit your CV in English.

Apply now

Key Responsibilities:

1. Core Development & Integration

The Middleware Backplane: Design and build sophisticated automation "recipes" in Workato (Backplane) and Power Automate to sync data between Business Central, Pipedrive, and Ooona.
Backend Engineering: Develop high-performance APIs and microservices using C# / .NET to handle data transformation and application logic.
Frontend Support: Build and maintain internal tools and dashboards using React to visualize integration health and business data.
Database Management: Write and optimize MS SQL queries and stored procedures to ensure data consistency across our Linux and Windows environments.

2. Mentorship & Team Growth

Knowledge Sharing: Act as a technical bridge for junior developers, helping them master backend concepts, API best practices, and complex SQL.
Code Quality: Lead peer code reviews with a focus on teaching, not just policing, ensuring the team understands the why behind clean, dry code.
Refactoring: Lead by example by refactoring legacy scripts into modern, tested, and documented services.

3. Security & Quality Assurance

Security Testing: Implement and test security protocols (OAuth, JWT, Encryption) to protect data moving between AWS and our on-premise servers.
Automated Testing: Build out Unit Tests (xUnit/nUnit/Jest) to ensure integrations are resilient to API changes or data spikes.

4. Technical Toolkit

Category	Ideally have knowledge and experience in these
Languages	C# (.NET Core), JavaScript / TypeScript, T-SQL.
Middleware	Workato (Backplane), Power Automate, Office Scripts.
Frontend	React.js, CSS/HTML.
Systems	MS Business Central, Pipedrive, Ooona.
Infrastructure	AWS (S3, Lambda, EC2), Linux & Windows Server.
Data/Testing	MS SQL Server, Power BI, xUnit/nUnit, OWASP Security standards.

How to Apply

If you are interested in the role, please send your up-to-date CV in English along with a covering letter to jobs@vsi.tv with the reference code #PL4830 in the subject line.

Due to the high number of applications for the position, we regret that we will only be able to respond to successful applicants.