Senior / Staff Backend Engineer (f/m/d)

Deine Aufgabe JTL is one of the leading providers of e-commerce software in the German-speaking region — with around 450 employees across the group and more than 50,000 customers across a wide range of industries. We develop scalable, flexible solutions for the online retail of the future, from ERP systems to shop and marketplace integrations. You'll join the team behind our Fulfillment Network — the backend that keeps orders, stock, and logistics flowing for thousands of merchants. We care about systems that stay up and get better with every release, and we keep ownership close: the people who build a service also run it. You'll fit in here if you like backend problems that carry real operational weight. This is a backend-first role — you think of yourself primarily as a backend developer, and the core of the work lives in the .NET / MongoDB space. You'll develop the REST API behind our Fulfillment Network (FFN) and Trade Network (TDN), products used by thousands of customers every day, and own the integration points where backend services and the JTL-Wawi client need to work together seamlessly. You think in systems and data flows rather than isolated tickets, switch comfortably between technologies, and thrive in a fast-moving, startup-like environment. The principle here is simple: you build it, you run it. You don't own the underlying hardware, but you own your application's operational readiness end to end — when outages happen, you resolve them the same business day. Stability and availability matter to you as much as shipping new features, and you take pride in making the product faster and more reliable with every iteration. Your Responsibilities Develop our FFN / TDN REST API further and own backend features end to end, from design to production Build the integration with JTL-Wawi, especially where backend services and client-side behavior need to work together seamlessly Support complex business and synchronization scenarios, and handle production incidents and customer-reported issues Operate and deploy the API through our pipelines — covering performance optimization, observability, and operational reliability Own the operational readiness of your application end to end: you build it, you run it, and you resolve outages within the same business day Was Du dafür mitbringst C#, modern .NET (.NET 8+), and ASP.NET Core are your primary stack — with solid, hands-on experience building and operating backend services in production You've built and maintained complex backend systems with a focus on robustness, maintainability, and scalability — using modern .NET patterns (async/await, dependency injection, clean architecture), CQRS, and Domain-Driven Design (DDD) You know MongoDB well (data modeling, performance optimization, high-volume datasets) and have strong SQL skills, including writing and optimizing complex queries for performance You design and consume REST APIs on both sides (Core & Connect), and you can identify and resolve bottlenecks across APIs, database access, and backend workflows You have hands-on observability experience with Prometheus and Grafana — metrics, dashboards, alerting, production analysis — and you resolve customer-reported issues pragmatically and reliably You've worked with AI-assisted development and agentic, automation-first engineering where it creates real value Good German communication skills Nice to have ERP or e-commerce background Logistics or fulfillment domain knowledge PHP — practical production experience, ideally within the Laravel ecosystem MariaDB / MySQL — data modeling and query optimization Livewire / Tailwind — no deep expertise required, but able to work independently WPF — practical experience working on existing desktop UI applications DevExpress — experience with component-based desktop UI development Was wir Dir bieten Remote-first within Germany, with the option to work remotely from eligible countries for up to 180 days per year Meal allowance of up to €115 net per month Ergonomic workspace allowance for your home office setup Regular team events, company-wide gatherings, and summer and Christmas parties to stay connected as a remote-first company EGYM Wellpass and JobRad subsidy Financial benefits including capital-forming payments (Vermögenswirksame Leistungen) and a company pension scheme Über uns JTL ist einer der führenden Anbieter von E-Commerce-Software im deutschsprachigen Raum – mit ca. 450 gruppenweiten Mitarbeiter:innen und 50.000 Kunden aus verschiedensten Branchen. Wir entwickeln skalierbare, flexible Lösungen für den Onlinehandel der Zukunft – von der Warenwirtschaft bis zur Shop- und Marktplatzanbindung. Fairness und Respekt sind bei uns gelebte Praxis. Du bist engagiert, neugierig, hast Lust auf Teamwork und Verantwortung? Du suchst einen Job, bei dem der Montag nicht der schrecklichste Tag der Woche ist? Dann freuen wir uns auf Deine Bewerbung! Einen kurzen Einblick in JTL findest du auch hier .