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.
Responsibilities
Design, develop, and maintain backend services and RESTful APIs using
.NET Core
Drive backend architecture decisions (modularity, scalability, reliability, observability)
Build reusable backend components, shared libraries, and utilities for future use
Translate product requirements into clean, maintainable, and well-tested code
Optimize services for
performance, throughput
, and
low latency
under high load
Ensure secure data handling, authentication/authorization, and best practices
Implement logging, metrics, and tracing using Azure-friendly observability tooling




Collaborate with database and platform teams to design efficient data models and integrations
Requirements
3+ years
of experience in backend development
1+years
of experience with
Claude Code
and/or
OpenCode
50% remote, 50% in Madrid
Strong proficiency in
C#
and the
.NET ecosystem
(ASP.NET Core, DI, middleware)
Solid understanding of
API design
, versioning, and documentation (OpenAPI/Swagger)
Experience with data access patterns and libraries (e.g.,
Entity Framework
Core, Dapper)
Knowledge of
SQL
and/or NoSQL databases and performance tuning
Experience with testing practices (unit/integration tests) and CI/CD workflows
J-*-Ljbffr

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