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# Fullstack Developer

- **Company:** Número De
- **Location:** Spain
- **Contract:** Permanent contract
- **Skills:** Query Performance, ASP.NET, .NET Framework, Application Programming Interfaces (APIs), Amazon Web Services, Automation of Tests, Microsoft Azure, C Sharp (Programming Language), Cloud Computing, Relational Databases, Database Schema, Key Management, OAuth, OpenID, Azure Active Directory, Next.js, Software Engineering, Systems Integration, TypeScript, Web Applications, Network Routers, ReactJS, Backend, Front End Software Development, Api Design
- **Published:** October 3, 2026
- **Apply:** https://www.adzuna.es/details/5907660737

## About the Role

* 8+ years of professional software development experience, with deep expertise in C# / .NET (ASP.NET Core).
 * 4+ years building production front-end applications with React, including Next.js (App Router, server components/actions, route handlers).
 * Strong understanding of Clean/Layered Architecture, domain modeling, and separation of concerns in non-trivial back-end systems.
 * Experience with relational databases and ORMs (EF Core or equivalent), including migrations and query performance.
 * Solid TypeScript skills and comfort working in a monorepo with shared, versioned internal packages.
 * Experience with cloud infrastructure (Azure preferred; AWS/GCP equivalents considered) - messaging/queues, object storage, secrets management.
 * Experience implementing or integrating OAuth2/OIDC-based authentication, ideally with enterprise identity providers (e.g., Microsoft Entra ID or similar).
 * Strong automated testing discipline: unit, integration, and contract testing on both back end and front end.
 * Comfortable working across the full stack without hand-offs - from database schema to API to UI.
 * Excellent communication skills and experience working in a small, senior, high-autonomy engineering team.

## Description

We are building a greenfield, document-driven lending platform that automates the full lifecycle of a loan application - from document intake and OCR-based extraction, through human-in-the-loop review, to final approval and downstream submission. The system is a modular monolith with a clear separation between backend services and multiple trust-boundaried web front ends, deployed natively on Azure.
We're looking for a senior full-stack engineer who is equally comfortable designing clean, testable back-end architecture in C#/.NET and building modern, production-grade UI in React/Next.js. You'll work across the stack: domain modeling, API design, background/async processing, and customer- and operations-facing web applications.