Jobs → Engineering → Backend Engineer

About the Role We are looking for a Backend Engineer to join Koinworx and work on a consumer-facing, server-driven UI backend for the PostNL app. Key Responsibilities • Design and implement RESTful APIs and GraphQL • Develop backend services using C#/.NET 8 • Work with AWS services including ECS Fargate, Lambda, SQS, SNS, DynamoDB, Redis • Implement security measures using OAuth/OIDC, JWT, and GDPR compliance • Collaborate with mobile, product, design, QA and engineering teams • Ensure end-to-end ownership of architecture, releases and production quality Requirements • 7+ years in Backend Development, including 5+ years in C#/.NET • Experience with server-driven UI and modular monolith architecture • Strong understanding of AWS services and DevOps practices • Experience with testing frameworks like xUnit, NSubstitute, FluentAssertions • Knowledge of security best practices and OWASP API guidance • Fluent English with strong communication skills • Experience working on consumer-facing backend with 100K+ active users Benefits • Visa sponsorship available