Role Description

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

*Envía tu CV a [email protected]*

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