We serve a diverse array of local and international brands both online and in-store, spanning various sectors. We have developed services that focus on revenue optimisation, performance enhancement, fraud prevention, and seamless payment orchestration. Furthermore, our solutions are designed with accessibility in mind, offering features that cater to the visually impaired, ensuring everyone can engage in the modern commerce landscape.
The Senior Backend Developer is responsible for designing, building and evolving the backend services that support PayXpert's Payment Gateway, Secure Store and other security‑sensitive components within the core payments platform.
The role spans mainly on the PHP‑based e‑commerce gateway but also on the Java/Kotlin payments platform components, working across these stacks to deliver and maintain secure transaction services.
The role operates with advanced technical expertise and high autonomy, developing complex backend features,



maintaining service integrity and ensuring the protection of sensitive transactional data within a regulated and compliance‑driven environment.
Design, develop, and maintain payment-oriented backend services across both PHP (e‑commerce gateway) and Java/Kotlin (core payments platform) codebases
Contribute to core payment backend applications with a strong focus on security-sensitive transaction flows.
Identify gaps or limitations in core backend services and propose technical solutions aligned with business needs.
Own backend components end-to-end, from design and implementation through production support. Act as a co‑owner of the PHP e‑commerce gateway, sharing accountability for its evolution, security and reliability.
Security, Reliability & Performance
Apply secure coding practices appropriate for transaction‑critical and sensitive data environments.
Participate in incident analysis and troubleshooting related to payment services.
Ensure backend services meet reliability, performance, and data integrity re

📌 Senior backend developer (Madrid)
🏢 Payxpert
📍 Madrid