Platform & Architecture Principal Software Engineer

Project Duration: 6-12 months, extension possible Commitment: Full-time JOB DESCRIPTION Our client is looking for a hands-on Principal Software Developer with deep computer science fundamentals and a pragmatic, product-oriented mindset. You combine strong architectural thinking with the ability to ship high-quality code thoughtfully and predictably. You are fluent in modern engineering practices, comfortable in heterogeneous, service-oriented and distributed environments, and focus on writing robust, maintainable code for systems that scale. You will help evolve a business-critical platform—leading the transition from a heterogeneous semi-distributed codebase to a strategically aligned, reliable, and scalable architecture. You will balance delivery speed with long-term sustainability and champion tools and techniques that multiply engineering effectiveness. What you'll do: - Design, build, and run a business-critical software platform using modern frameworks and programming languages - Spearhead the migration from a semi-distributed codebase to a unified, scalable architecture - Analyze trade-offs, risks, dependencies, and user value to drive technical decisions - Solve complex technical problems hands-on, not from the sidelines - Operate close to production: build it, ship it, support it - Champion clean code, test coverage, and performance-first thinking - Evaluate and apply emerging developer tools where they provide real leverage (e.g., GitHub Copilot, GPT agents, etc.) Who we're looking for: - 8 to 12 years of professional experience in software development with at least 80–100% of your last 2-3 years spent coding, shipping, and deploying - Expert knowledge of C#/.NET Core - Proven track record of delivering production-grade systems - Proficient in functional programming and strong static typing (F#, Scala 3, Rust, Haskell, Kotlin, OCaml, etc.) - Applied architectural knowledge : modular monoliths, microservices, event-driven systems, actors, etc. - Confident working with relational databases (schema design, migrations, tuning) - Familiarity with modern delivery stacks : Git, GitOps, CI/CD, Docker, etc. - Strong communication and collaboration skills; self-starter attitude - Fluent English (C1/C2) ; German is a strong plus Nice to Have - Experience with Kubernetes and Infrastructure-as-Code tools (e.g. Terraform, Pulumi) - Familiarity with AI-assisted engineering tools (Copilot, GPT, linters, analyzers) - Experience with platform abstraction, developer enablement, or internal tooling #J-18808-Ljbffr