> Markdown version of [/jobs/ext/2525797-software-development-engineer](https://www.wearedevelopers.com/jobs/ext/2525797-software-development-engineer). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md).

---

# Software Development Engineer

- **Company:** Número De
- **Location:** Madrid, Spain
- **Contract:** Permanent contract
- **Skills:** Java (Programming Language), User Authentication, Software Debugging, File Systems, Distributed Systems, Performance Tuning, Software Engineering, Multithreading, Enterprise Software Applications, Backend, Build Management, Information Technology
- **Published:** August 1, 2026
- **Apply:** https://www.adzuna.es/contact-us.html

## About the Role

+ 5-10 years of professional experience developing enterprise software applications using Java.
 + Strong expertise in designing, debugging, and optimizing complex software systems, including performance, scalability, multithreading, and operating system interactions.
 + Proven experience building reliable, high-performance backend systems using modern software engineering principles and best practices.
 + Excellent analytical thinking and problem-solving skills, with the ability to diagnose complex production issues efficiently.
 + Experience working in distributed or international engineering teams with strong written and verbal communication skills.
 + Bachelor's degree or higher in Computer Science or a related technical discipline.
 + Solid understanding of Unix/Linux operating systems and file systems.
 + Experience working on infrastructure domains such as security, authentication, monitoring, performance optimization, or scalability is highly desirable.
 + Exposure to quality assurance practices or software testing methodologies is considered an advantage.

## Description

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Software Development Engineer, Core Infrastructure based in Spain.
This is an excellent opportunity for an experienced Software Development Engineer to contribute to the core infrastructure of a sophisticated enterprise platform. In this role, you will design and build secure, scalable, and reliable backend systems that support mission-critical applications while improving product resilience, security, and operational excellence. Working within a collaborative international engineering environment, you will partner with cross-functional teams to solve complex technical challenges, influence engineering best practices, and deliver innovative solutions that have a direct impact on product performance and customer success. The position is ideal for engineers who enjoy tackling large-scale distributed systems, driving technical improvements, and mentoring engineering excellence.
Accountabilities

 + Architect, design, and develop core infrastructure components that enhance the security, scalability, reliability, and maintainability of enterprise software products.
 + Lead the delivery of complex technical initiatives by defining clear implementation strategies, coordinating with multiple engineering teams, and managing technical dependencies.
 + Investigate, troubleshoot, and resolve critical production issues, identifying root causes and implementing long-term improvements to strengthen system robustness.
 + Collaborate with Product Management, Engineering, Customer Success, and other stakeholders to translate business and technical requirements into scalable software solutions.
 + Contribute to the evolution of engineering standards, development processes, and technical best practices across the organization.
 + Support customer-facing teams by analyzing complex production environments, identifying effective solutions, and helping resolve high-priority technical challenges.
 + Continuously improve platform capabilities related to security, authentication, monitoring, diagnostics, and operational resilience.