Backend Developer (.NET or Java / Cloud)

Description

Job Summary: We are seeking a Backend Developer to drive the evolution of a mortgage platform, optimizing key functionalities and improving operational efficiency. Key Highlights: 1. You will participate in the evolution of a leading mortgage platform. 2. You will join an innovative environment incorporating AI and a rules engine. 3. You will work on the design and development of REST APIs and microservices. Are you interested in continuing your growth as a **Backend Developer** within a leading banking and financial services company? At **OXIGENT TECHNOLOGIES**, we are recruiting a **.NET Developer**, whose mission will be to drive the evolution of one of the main platforms in the mortgage domain. You will participate in the **optimization of key functionalities and improvement of the system’s operational efficiency.** Additionally, you will join an **innovative environment**, working on the integration of new technologies, including **AI-based solutions**, and developing a rules engine enabling more agile, flexible, and precise design and management of **mortgage models.** **What will your main responsibilities be?** * Design and develop highly available REST APIs using .NET (ASP.NET Core), ensuring scalability and resilience. * Participate in building a new mortgage-sector platform from scratch. * Define and implement microservice-based architectures. * Develop and evolve the mortgage core, modernizing legacy components and creating decoupled services. * Design a business rules engine for flexible management of mortgage models. * Integrate AI solutions into the platform. * Work in cloud environments (AWS/GCP) with container-based and managed-service architectures. * Ensure software quality through TDD, automated testing, and security best practices (OWASP). * Guarantee compliance with demanding SLAs, system performance, and observability. * Collaborate with cross-functional teams in an agile environment (squad). **What do you need to succeed?** * 5+ years of production backend development experience (Senior: 7+ years). * 2+ years of experience developing highly available REST APIs. * Prior experience in projects with strict SLAs and medium-to-high transaction volumes. * .NET 8+ with ASP.NET Core. * Design and implementation of REST APIs following OpenAPI 3.x. * Microservice patterns: API Gateway, circuit breaker (Polly), retry, bulkhead, idempotency. * Public cloud (GCP or AWS): serverless containers (Cloud Run, App Service, ECS), managed databases, messaging (Pub/Sub, Service Bus, SQS). * Relational databases: PostgreSQL and/or SQL Server. Relational design, query optimization, indexing, partitioning. * Containers: Docker, best practices for minimal and rootless images. * Asynchronous messaging and event-driven patterns. * TDD / BDD. Unit testing: JUnit, xUnit, NUnit. **What do we offer?** * Permanent contract. * Competitive salary aligned with experience (€42,000–€51,000 gross annual). * Flexible working hours. * Training voucher to support professional development in areas of interest. * Private health insurance. * Flexible compensation applicable to health insurance, meals, transportation, childcare, and training. * Gym and sports activity access across Spain with discounts. * And many other benefits! Join the Oxigent team! A company committed to sustainability and equal opportunities, where talent and technology know no gender. Location: Spain \- Madrid Date: 22/06/2026 Salary: €46,000 Employment Type: Employee