C# Backend Developer – .NET, ASP.NET, SQL Server

RockstarDevelopers GmbH

. Contribute to client projects at large companies, embedded within their teams .

Posted 11/2/2026full-timeGermanyMid-LevelSeniorWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates extensive experience in Backend Development with C# and .NET, alongside proficiency in Microsoft SQL Server and T-SQL for data modeling. Capable of collaborating effectively in German within client teams and enhancing applications in financial and identity management domains.

Highest-signal resume keywords

C# DevelopmentASP.NET Web ApplicationsMicrosoft SQL ServerT-SQL Data ModelingGerman Language Proficiency (C1)

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

C#ASP.NETMicrosoft SQL ServerT-SQLGitAutomated TestingClaude CodeCopilotCursorData Modeling

Soft Skills

CollaborationCommunication

Tools & Technologies

Claude CodeCopilotCursorGit

Industry Keywords

Identity ManagementFinancial SystemsBilling SystemsTransportation IndustrySAP User Management

Tech Stack

Tools & technologies

ASP.NETMS SQL ServerNeo4jReactSQL.NET

About the role

Key responsibilities & impact

Contribute to client projects at large companies, embedded within their teams
Backend development with C# and .NET
Develop web applications with ASP.NET
Design and implement data models using Microsoft SQL Server and T-SQL, including performance optimization
Develop interfaces and integrate systems
Enhance existing applications, such as billing and financial systems or identity management solutions
Generate, review, and refactor code using Claude Code, Copilot, or Cursor
Coordinate with Product Owners, business stakeholders, and operations teams
Work in German in meetings and documentation
Collaborate as part of the client’s team

Requirements

What you’ll need

At least three years of professional experience as a developer, counted from completion of vocational training or a degree
C# and .NET, with at least three years of production experience within the last five years
Microsoft SQL Server and T-SQL, including data modeling
Web applications with ASP.NET
Git, automated testing, and clean handover to operations and the team
German at C1 level or higher
Hands-on production experience with Claude Code, Copilot, or Cursor is required
Willingness to work in the client’s team in German, both in meetings and documentation
Preferred, but not required: One Identity Manager or other identity and access management systems
Preferred, but not required: SAP user and role management or SAP connectors
Preferred, but not required: Financial, billing, or controlling systems
Preferred, but not required: Experience in the railway or transportation industry
Preferred, but not required: LLM integration into applications (RAG, tool calling, agents)
Preferred, but not required: React
Preferred, but not required: Graph databases such as Neo4j, as well as Cypher or Gremlin

Benefits

Comp & perks

Primarily remote, with office access if you prefer
MacBook (unless the client provides its own hardware)
A variety of clients and projects
Internal upskilling in AI development
Permanent employment contract
Direct points of contact: the founders