Senior Software Engineer - Backend - Billing Team

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 Engineer - Backend - Billing Team based in Spain.

Join a small, high-impact engineering team building and scaling reliable backend systems for a rapidly growing digital product.

Take ownership of backend features, APIs, services, and business logic that support critical product capabilities.

Work on complex technical challenges while keeping simplicity, reliability, and long-term scalability at the center of engineering decisions.

Contribute across the development lifecycle, from architecture and implementation through testing, code reviews, and production support.

Help strengthen infrastructure resilience and redundancy as systems and workloads continue to scale.

Collaborate closely with experienced engineers and product stakeholders in a flat, entrepreneurial environment.

Have meaningful influence over technical direction and product evolution while working with a modern cloud-native technology stack.

Accountabilities

• Develop, maintain, and improve backend features and services supporting the product.
• Design and implement robust backend APIs and business logic for both new and existing product capabilities.
• Build services with a strong focus on simplicity, reliability, scalability, and maintainability.
• Participate actively in code reviews, providing constructive feedback and incorporating feedback from other engineers.
• Design, test, consume, and support APIs for production web services.
• Contribute to improving the reliability, redundancy, and resilience of production infrastructure.
• Work across a diverse technology environment and identify opportunities to improve systems, processes, and engineering practices.
• Stay informed about emerging technologies and evaluate opportunities to apply them effectively within the technical environment.
• Collaborate closely with teammates and other stakeholders to deliver high-quality projects efficiently.
• Take ownership of technical challenges, analyze problems independently, and drive solutions through to completion.

Requirements:

• Strong professional experience in backend software engineering, with expertise in at least one general-purpose programming language.
• Highly proficient in database design and development, with experience working with both relational and NoSQL databases such as Scylla and Redis.
• Hands-on experience creating, testing, consuming, and supporting APIs for web services.
• Comfortable working with AWS, Linux, Docker, Kubernetes, and continuous deployment workflows.
• Ability to work effectively within a multi-language technology stack and adapt to different programming environments.
• Experience with Node.js and TypeScript or Rust is an advantage, but not required.
• Basic frontend development knowledge and an understanding of how backend and frontend systems interact.
• Experience with modern frontend frameworks is a plus.
• Strong written and verbal communication skills, with the ability to collaborate effectively in a technical team.
• Self-directed and analytical approach, with strong problem-solving abilities and a willingness to take ownership.
• Entrepreneurial and pragmatic mindset, with the ability to move quickly while maintaining high engineering standards.
• Comfortable working in small teams where individual contributors have significant responsibility and influence.

Benefits:

• Startup-style environment with a flat organizational structure.
• Opportunity to work closely with founders and experienced team members.
• Significant influence over product development and technical evolution.
• Opportunity to build technology that reaches and impacts a large global audience.
• Equity package offering an opportunity to share in the long-term success of the business.
• Access to the technology and tools needed to perform effectively.
• High degree of ownership and autonomy in your work.
• Collaborative environment where individual contributions have a meaningful impact.
• Opportunity to work on complex backend, cloud, and infrastructure challenges in a rapidly scaling product environment.