As a Senior .NET Backend Developer, you will drive architectural decisions for our flagship product's server-side platform. You will work closely with Frontend and UX/UI teams to design and deliver robust APIs, ensure scalability, and maintain high performance and reliability.Freelance or permanent.ResponsibilitiesDesign, develop, and maintain backend services and RESTful APIs using.NET CoreDrive backend architecture decisions (modularity, scalability, reliability, observability)Build reusable backend components, shared libraries, and utilities for future useTranslate product requirements into clean, maintainable, and well-tested codeOptimize services forperformance, throughput, andlow latencyunder high loadEnsure secure data handling, authentication/authorization, and best practicesImplement logging, metrics,



and tracing using Azure-friendly observability toolingCollaborate with database and platform teams to design efficient data models and integrationsRequirements3+ yearsof experience in backend development1+yearsof experience withClaude Codeand/orOpenCode50% remote, 50% in MadridStrong proficiency inC#and the.NET ecosystem(ASP.NET Core, DI, middleware)Solid understanding ofAPI design, versioning, and documentation (OpenAPI/Swagger)Experience with data access patterns and libraries (e.G.,Entity FrameworkCore, Dapper)Knowledge ofSQLand/or NoSQL databases and performance tuningExperience with testing practices (unit/integration tests) and CI/CD workflows

📌 Ingeniero Senior.Net (Madrid)
🏢 RuiderIA
📍 Madrid