Backend Engineer

About 0TO9:Team Is AllIdeas matter – but people make them real. In finance, that’s harder than it should be. Innovation shapes how we live, but progress is slowed by complexity, regulations, and outdated systems. Too often, great people go elsewhere.0TO9 exists to change that.We’re a fintech venture builder and investor – a bank for entrepreneurship, founded in Stockholm in 2025 by serial entrepreneur Oliver Hildebrandt.Our mission: bring the right people, skills, and resources together so fintech founders can focus on building. From capital and compliance to tech and talent, we create an infrastructure for success.Numbers are the building blocks of finance and with zero to nine, we can build anything. Our name says it all: From you to a team. From idea to impact. From now to what’s next.With offices in Stockholm and Berlin, operations across the Nordics, and a growing portfolio – we’re just getting started.About the roleAt 0TO9, you won’t just build services - you’ll shape the core banking platform powering the next wave of fintech ventures. This is a chance to work with and solve complex problems at scale, and be part of building something from the ground up.Build and maintain C#/.NET Core microservices on AWS ECS for the banking platformCollaborate with product managers, architects, and engineers to deliver high-performance APIsWrite clean, testable code following SOLID principlesApply DDD and CQRS to create modular, scalable, and maintainable systemsDesign event-driven communication using NATSEnsure reliability through idempotency, retries, and self-healing servicesImplement observability: logging, metrics, tracing, and performance monitoringWorking with both relational (MS SQL Server) and NoSQL (DynamoDB) databases.Contribute to secure design (auth, secrets, compliance)Improve CI/CD, containerized workflows, and engineering practicesAbout youWe think you’ll be a great fit if you:Have backend experience working with microservices and distributed systems, C# and .NET Core and AWSTake ownership, challenge unclear requirements, and prioritize reliabilityHave applied DDD and CQRS in real-world systemsUnderstand event-driven architectures (ideally with NATS)Care about writing clean, maintainable, testable codeNice to have:Previous fintech or banking industry experienceHands-on experience with integration testing, contract testing, or end-to-end service testingKnowledge of observability tools and testing strategies for microservicesUnderstanding of cloud security, governance, and complianceWhat we offer:Be part of the leading fintech venture builderA dynamic, entrepreneurial, international and fast-paced environmentBeautiful office in the heart of StockholmStrong opportunities for growth and development