Middle/Senior .NET Developer

Sigma Software is seeking a Middle/Senior .NET Developer to join a product-focused engineering team delivering solutions for the European construction industry. You will contribute to implementation as well as architecture discussions, technical improvements, and product evolution. You will be part of a mature delivery team with predominantly Senior-level specialists, collaborating closely with architects, QA engineers, DevOps experts, and Product Owners.

Responsibilities

• Design, develop, and maintain robust back-end solutions using C# and .NET
• Participate in architecture discussions and contribute to technical solution design
• Develop and integrate RESTful APIs and SOAP web services
• Work on core modules, perform refactoring when necessary
• Collaborate with developers, QA engineers, DevOps specialists, architects, and Product Owners
• Clarify business and technical requirements with internal and Customer-side teams
• Write and maintain unit, API, and integration tests
• Participate in peer code reviews and follow engineering best practices
• Investigate and introduce new technologies and technical improvements
• Troubleshoot issues across application, infrastructure, and database layers
• Prepare and maintain technical documentation
• Contribute to front-end-related tasks using Angular and TypeScript when needed

Requirements

• 4+ years of commercial software development experience with C# and .NET

• Strong experience designing, developing, and integrating Web APIs, including RESTful APIs and SOAP services

• Solid understanding of OOP, SOLID principles, and common design patterns

• Strong knowledge of Microsoft SQL Server and T-SQL

• Practical experience with LINQ, ADO.NET, and Entity Framework

• Experience working with event-driven systems and message brokers

• Experience writing and maintaining unit, API, and integration tests

• Experience with Angular or another modern front-end framework/library

• Good knowledge of TypeScript

• Understanding of front-end architecture, maintainability, and performance optimization

• Strong troubleshooting and debugging skills across application, database, and infrastructure layers

• Confident Git usage, including branching strategies, pull requests, and code reviews

• Intermediate or higher English level

• Strong communication skills and ability to work collaboratively in a cross-functional environment

• Nice to have

• Experience with NoSQL databases

• Experience using AI-assisted development tools such as GitHub Copilot or Claude