Backend Developer (.NET)

Overview We are looking for a .NET Developer with solid experience in designing and building scalable, testable, and maintainable backend services. You will focus primarily on engineering robust APIs and service layers using .NET , while occasionally contributing to Windows desktop application development where needed.

This role is ideal for engineers who care deeply about clean architecture, automation, and solving real-world problems through backend excellence. You’ll collaborate cross-functionally to deliver reliable, performant systems that power key business applications.

/ This is a hybrid role requiring 3 days per week in our Barcelona office.

First 90 Days 30 days – Ramp up on Sage’s architecture, services, and backend standards. Understand deployment flows and key integrations.

60 days – Actively contribute to key product initiatives and features in development. Demonstrate increasing ownership and impact within the engineering team. Begin contributing meaningful code to the main product codebase.

90 days – Take full ownership of feature delivery, from planning to release. Lead code reviews and ensure adherence to quality and best practices. Participate in architectural discussions and help shape technical direction.

Meet the Team You’ll report to an Engineering Manager based in Barcelona and collaborate with colleagues across backend, desktop, QA, DevOps, and product teams. The team works in a global Agile structure and values code quality, autonomy, and continuous improvement.

How Success Will Be Measured Consistent delivery of performant and reliable .NET Core backend services

Active contribution to service design, performance tuning, and codebase health

Impactful collaboration with cross-functional teams on features and deployments

Adoption and promotion of architectural patterns and engineering standards

Skills You’ll Gain Deep expertise in .NET Core services, clean architecture, and API design

Experience collaborating on desktop + backend integrations

Broader exposure to DevOps, CI / CD, and containerization practices

Involvement in architectural decision-making and backend scaling challenges

Snapshot of Your Day-to-Day You’ll design and develop backend services in .NET Core , implement APIs and data layers, and integrate with third-party systems. You may also support WPF-based desktop clients, participating in service integration and modernization. You’ll attend standups, code reviews, and contribute to CI / CD and observability efforts.

Qualifications 5+ years of experience in professional backend development with C# and .NET Core

Expertise in building and optimizing RESTful APIs and service layers

Solid understanding of clean architecture, async programming, and testing

Proficient in SQL Server, Entity Framework Core, and query optimization

Experience working in Agile teams with CI / CD pipelines

Fluent in English; Spanish fluency is a plus

Experience with WPF / MVVM is a strong plus

Tech Stack You’ll Work With Languages & Frameworks : C#, .NET Core, ASP.NET Core, Entity Framework Core, LINQ

Backend Patterns : REST, Clean Architecture, CQRS, async programming

Databases : SQL Server, relational data modelling, performance tuning

Desktop : WPF, MVVM, XAML

DevOps & Tooling : Git, CI / CD pipelines (Azure DevOps or equivalent), Docker (optional), monitoring tools

Benefits Flexible benefits : exchange part of your salary and make tax savings on health insurance, meal and transport vouchers, childcare, and training.

Well-being : Free access to the Calm app (for up to 5 users), 24 / 7 counselling, and emotional support from our Healthy Mind Coaches. We also offer self-care and parenting resources through the Cleo app.

Flexible working : flexibility of working one hour in, one hour out, shortened workdays on Fridays and during the summer, and the opportunity to work from over 40 countries for up to 10 weeks per year through our Work Away program.

Annual leave : 23 working days of vacation, 5 paid days per year for volunteering, and 5 additional paid days annually for personal or professional development.

Extended leave : 7 extra days of maternity leave and 5 extra days of paternity leave, on top of the legal allowance, available after one year of service.

Financial support : Life and disability insurance, salary advances of up to 3.5 times your net monthly pay, a €300 net marriage bonus, and access to Sage's employee stock purchase plan at a discounted rate.

Health and Safety Responsibilities

Fostering the safety culture by leading with your own example.

Following established safety procedures and reporting potential hazards promptly helps maintain a secure and efficient workplace.

Participating in safety training sessions and adhering to preventive guidelines and procedures, the objective is minimizing risks and protecting yourself and the rest of your colleagues.

Seniority level Mid-Senior level

Employment type Full-time

Job function Engineering and Information Technology

Industries

Software Development

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