# Senior Software Engineer, Full-stack JavaScript > Upstream · Gerakas, Greece (Hybrid) · Full-time · Posted 2026-01-09 **Workplace:** hybrid **Department:** Engineering ## Description **Who we are** Upstream is a global leader in mobile marketing automation and digital service innovation, enabling Mobile Network Operators (MNOs) and brands to grow revenue, improve customer engagement and succeed in the digital economy. With over two decades of experience and operations spanning 45+ markets across Africa, Latin America, Asia, Europe, and the Middle East, we are a trusted partner to more than 60 MNOs worldwide. Headquartered in Athens, Greece, and with regional hubs in London, Dubai, Johannesburg, Lagos, São Paulo and Rio de Janeiro, Upstream combines global expertise with deep local insight. Our end-to-end approach encompasses strategy, creative development, technical deployment, campaign execution, and ongoing optimization, ensuring seamless, scalable, and performance-driven service delivery. **The role** In the context of our growing business and ongoing project needs, we are looking for an enthusiastic Senior Software Engineer to join our Software Development team in Athens, Greece. Our HQ offices are based in Gerakas and we have adopted a hybrid work mode. As a Senior Software Engineer you will be part of a very competent team that works on mission – critical applications throughout the entire development lifecycle, from concept and design, to developing and delivering to production. You will use a modern JavaScript tech-stack, such as React/Next.js, Express.js, to build both the public facing and internal application modules of our products. You will work in a cross-functional team with QA Automation and DevOps Engineers, who are integral to our CI/CD process. You will collaborate with UI/UX Designers and Product Managers to produce our world-class Marketing Technology Platform. We use the industry best practices and prioritize providing an exceptional developer experience, which means that you will have the tools and support you need to thrive in your role. You'll have the opportunity to work with top-tier private cloud infrastructure like Kubernetes clusters and dedicated "performance labs" to ensure that we meet our Platform's performance and scalability needs. We believe in fostering an environment that allows you to reach your full potential and deliver high-quality work with confidence. **Your main responsibilities will be to:** - Write well designed, testable, efficient software modules. - Translate business specifications, designs and wireframes into high-quality code. - Create reusable components for the frontend component library. - Prepare and produce releases of software modules. - Troubleshoot and support existing products and infrastructure. - Review, test, and debug code. - Support continuous improvement by investigating alternatives and technologies and presenting these for architectural review. - Support and coach junior developers in writing clean, maintainable and efficient code. ## Requirements - Computer Science, Engineering or equivalent degree. - 5+ years of full time professional Full Stack / Web Development experience. - Hands-on experience in designing and developing full stack applications using JavaScript, Typescript. - Hands-on experience in a popular library/framework such as React, Next.js, Express. - Experience with HTML, CSS and responsive design. - Experience with designing and consuming HTTP APIs. - Experience with SQL and NoSQL databases and caches (e.g. MongoDB, PostgreSQL, Elasticsearch, Redis, Memcached). **Experience in the following will be extra appreciated:** - Laravel PHP framework. - Messaging systems such as Kafka. - CI/CD tools and processes. _You will be an excellent fit for our team if you are:_ - Strong team player with good communication skills. - Eager to work with leading-edge technologies. - Analytical thinker with attention to detail. - Reliable and dedicated professional with clear thinking and strong attention to detail. - Able to multitask and thrive in a dynamic environment as well as balance and prioritize activities to ensure critical items are addressed. ## Benefits We offer a competitive base salary and benefits, directly dependent on the candidate’s qualifications and skills. The real excitement comes from working closely with a dynamic, smart, agile, and highly motivated team in a competitive and fast-paced environment. Follow us on [LinkedIn](https://www.linkedin.com/company/15514?trk=tyah&trkInfo=clickedVertical%3Acompany%2CentityType%3AentityHistoryName%2CclickedEntityId%3Acompany_company_company_company_company_company_company_company_15514%2Cidx%3A1) and stay updated on our latest news. Upstream is an equal-opportunity employer. The Company does not discriminate on the basis of race, color, creed, pregnancy, religion, gender, national origin, age, disability, marital, or any other legally protected status. The Company also makes reasonable accommodations for disabled employees. Finally, the Company prohibits the harassment of any individual based on their protected status. This policy applies to all areas of personnel actions including recruitment, hiring, training, promotion, compensation, benefits, transfer,and social and recreational programs ## Apply [Apply at Upstream](https://apply.workable.com/upstream/j/53860C5FDB/apply) --- Powered by [Workable](https://www.workable.com)