Full-Stack Engineer (.NET / React) – AI-Driven Delivery

Seargin Ltd; Warszawa; Hybrid; PLN 180,000 - 270,000; Full time

Benefits offered by this job

B2B Contract

MultiSport

Private Medical Care

International Projects

Job summary

Seargin Ltd in Warsaw is seeking aSenior Full-Stack Engineer to design and implement scalable architectures across .NET and React stacks. You will translate clear specifications into working code using AI-assisted tools and validate code through rigorous testing and security checks.

You will collaborate with PMs and BAs, participate in client workshops, and ensure fast, predictable delivery within a dynamic, international firm. Strong Polish and English communication are essential.

Qualifications

• 5+ years of commercial full-stack engineering experience with independent responsibility for project architecture.
• Very good knowledge of .NET and C#, including Web API and Entity Framework Core.
• React with TypeScript for modern frontend development.
• Proven AI-assisted code generation and refactoring workflow with explainable validation.
• Experience with spec-driven or test-driven development and solid test coverage.
• Good knowledge of REST APIs, SQL Server or PostgreSQL, Git, and CI/CD.
• Ability to work independently and own delivery in a small team.

Responsibilities

• Design and maintain scalable architecture across .NET backend and React frontend.
• Translate specs into working code using AI-assisted tools.
• Review and validate code with testing, security, and readability checks.
• Collaborate with PMs, BAs, and client workshops; participate in demos.
• Coordinate with DevOps on CI/CD and environments; partner with QA on testing.

Skills

Full-Stack

.NET & C#

React TS

AI-assisted Development

Spec-Driven TD

REST APIs

Relational DBs

Delivery Ownership

Polish & English

Tools

Git

CI/CD

Azure

Job description

Seargin Ltd in Warsaw is seeking aSenior Full-Stack Engineer to design and implement scalable architectures across .NET and React stacks. You will translate clear specifications into working code using AI-assisted tools and validate code through rigorous testing and security checks.

You will collaborate with PMs and BAs, participate in client workshops, and ensure fast, predictable delivery within a dynamic, international firm. Strong Polish and English communication are essential.