**Backend Engineer – Trunkstar** *Madrid \| Full\-time \| Fast\-paced SaaS scale\-up \| Office next to Ronda de la Comunicación* Trunkstar is a fast\-growing SaaS platform used by connectivity providers across the world. Our customers include global carriers, ISPs, MSPs, and infrastructure providers who depend on Trunkstar to automate availability checks, pricing, quoting, ordering, and operational workflows. We help them run their entire connectivity business from one platform with accuracy, speed, and scale. We are expanding our engineering team in Madrid and are looking for a Backend Engineer who wants to help build the software foundation of modern global connectivity. If you enjoy working in a fast\-paced environment, solving complex technical challenges, and learning new technologies, this role will suit you well. What you will do * Build and maintain scalable backend services that power Trunkstar * Work on high\-performance systems that process millions of data points from global carriers * Integrate with external telecom APIs for availability, quoting, ordering, and provisioning * Improve and extend our microservices architecture using Go, PHP/Symfony, MongoDB, and RabbitMQ * Contribute to performance optimizations, architecture decisions, and new product capabilities * Collaborate with an experienced international engineering team where your work makes a direct impact What we are looking for * Strong experience in backend development. Go or PHP experience is preferred but strong fundamentals matter most * Experience with databases. MongoDB experience is a plus * Understanding of microservices, distributed systems, or event\-driven architectures * Someone who thrives in a dynamic environment and enjoys learning new technologies * A proactive builder who likes taking ownership and solving difficult problems * Well spoken English is required since the team and our customers are international What we offer * The opportunity to build core parts of a platform used by customers around the world * A fast\-moving environment with large opportunities for technical and personal growth * A chance to contribute to our expansion into Spain and shape our presence in Madrid * An office next to Ronda de la Comunicación with easy access and a great working environment * A culture focused on ownership, autonomy, and real impact * Competitive compensation and a hybrid work setup If you want to help build the future of global connectivity software, we would love to hear from you. Job Type: Full\-time Pay: 3,750\.00€ \- 5,000\.00€ per month Application Question(s): * Do you live in or near Madrid? Language: * English (Required) Work Location: In person