Senior Backend Engineer - C# (f/m/d)

Your tasks

JTL is one of the leading providers of e-commerce software in the German-speaking region. With our Warehouse Management System (WMS), we support customers in processing thousands of orders every day – from goods receipt and picking through to shipping. Performance, stability and reliability are business-critical here.
Today, our WMS is closely connected to the ERP system. Step by step, we are advancing the architecture and creating clearly defined interfaces, modern APIs and new cloud services. In doing so, we are modernizing a system used in production without disrupting ongoing operations – a technical challenge with a direct impact on our customers.
To support this, we are looking for reinforcement for a team of six developers and two QA engineers. We work in two-week sprints, make technical decisions together and actively use modern AI tools such as Claude Code and GitHub Copilot in our everyday development work.

• You help shape the step-by-step modernization of the WMS monolith and make sound technology decisions
• You gradually separate the WMS from the ERP system and define the interfaces through which both systems will communicate with each other in future
• You develop the API layer and the hub applications (e.g. warehouse assistant, dashboard) through which we open up the monolith and extend it with cloud functions
• You develop, operate and maintain these services as well as the WMS application itself, both in the backend and the frontend
• You share your knowledge within the team and help shape our technical standards

What you bring

• Several years of experience as a Senior Software Engineer with responsibility for architecture and technology decisions
• Very good knowledge of C# and the .NET ecosystem (.NET 10+)
• Experience in modernizing evolved software landscapes, e.g. through modularization, API-based integration and step-by-step migration
• Sound knowledge of developing and connecting APIs (REST, GraphQL) as well as of Microsoft SQL Server
• High quality standards with a focus on automated tests and operating your own services (“You build it, you run it”)
• Experience with AI-assisted software development or the willingness to use modern AI tools in everyday development work
• Good written and spoken English skills

These are an advantage

• Experience with React and TypeScript
• Knowledge of desktop development with WPF
• Experience with messaging systems such as Azure Service Bus, RabbitMQ or Kafka
• Knowledge of cloud and DevOps topics, in particular Azure, Docker, Kubernetes and CI/CD
• Experience in the area of observability (monitoring, logging, tracing)
• Domain knowledge in e-commerce or warehouse logistics