You will take ownership of a core backend system that is critical to the company and our customers. This system operates independently from our main platform and supports key business workflows under strict client and regulatory constraints. While the platform is constrained by customer requirements, there is room to improve internal structure, reliability, and tooling over time.

Your responsibilities

- Technical ownership of a core, isolated .NET system used in production.
- Maintain, extend, and stabilize an existing codebase built on .NET Framework 4.8.
- Ensure reliability, performance and correctness.
- Diagnose and resolve complex production issues.
- Collaboration with other engineering teams.
- Make pragmatic decisions balancing risk, maintainability, and business needs.
- Improve code quality and internal structure where possible.

What we are looking for





- 5 years plus experience building and maintaining production systems with .NET.
- Strong experience with .NET Framework (not only .NET Core / .NET 6+).
- Solid understanding of relational databases and transactional systems.
- Ability to work with legacy or constrained systems.
- Experience owning systems that are business critical.
- Methodical approach to debugging and problem solving.
- Comfortable working autonomously with high ownership.
- Advanced level Spanish and English.

Tech Stack

- Language & Platform: C#, .NET Framework 4.8 - Data: PostgreSQL or similar relational databases - Infrastructure: Windows-based services, Docker where applicable, and cloud infrastructure on AWS or GCP.

Location

- Barcelona, Spain > along with a hybrid working model

📌 Senior .NET Engineer (Barcelona)
🏢 Ersilia
📍 Barcelona