We're looking for a Senior Software Engineer to join our tech team and help build the future of neuro-contextual advertising at global scale. At Seedtag, our mission is to transform advertising by proving that effectiveness and user privacy can truly coexist. As the leading Neuro-Contextual Advertising Company, we combine Artificial Intelligence, Natural Language Processing, Computer Vision, and neuroscience to understand not only what content is about, but how it makes people feel and what they intend to do next. Our proprietary AI, Liz, enables brands to connect with audiences across the open web and Connected TV without cookies or user tracking. Founded in 2014 by two ex-Googlers, Seedtag has grown to 500+ Seedtaggers in 17 countries, backed by €250M in funding, and operates today as a global ad-tech leader. If you enjoy solving complex engineering challenges and building AI-driven systems at scale, you'll feel right at home here. As our Senior Software Engineer, you will join our five-person Contextualization Platform team, building the technology that understands content across the open web, Connected TV (CTV), and in-app environments. You'll develop high-performance backend systems and turn AI innovations into production solutions that power contextual advertising at scale. Backend Development: Design, build, and maintain high-throughput, low-latency services using Golang, supporting an RTB ecosystem handling over 500K queries per second. Transform Data Science experiments, LLM capabilities, and AI-driven ideas into reliable production systems. Scalable Architecture: Develop APIs, services,



and data pipelines that process large volumes of contextual data efficiently. Innovation & Experimentation: Prototype, test, and iterate on new approaches to contextual understanding across OpenWeb, CTV, and in-app environments. Contribute to architectural decisions and continuously improve system performance, reliability, and scalability. Cross-Functional Collaboration: Work closely with Data Scientists, AI teams, and Product Managers to deliver solutions with measurable business impact. Write clean, maintainable code while balancing quality, speed, and evolving business priorities. We test early, iterate often, and learn fast. We Are Data-Driven Data informs our decisions and helps us continuously improve our systems and results. Core Language: Go / Golang. Python, Node.js, TypeScript. AI & Machine Learning: LLM APIs, embeddings, RAG, ML model integration. Cloud infrastructure, monitoring, Infrastructure as Code (e.g. Terraform). Strong hands-on Golang experience, building and maintaining backend services in production. Experience with cloud infrastructure, observability, and production system monitoring. Strong problem-solving skills and a pragmatic approach to delivering reliable, maintainable software. It Would Be a Plus If You Have experience with Python, Node.js, or TypeScript. Have experience processing large-scale data or building real-time advertising systems. A key moment of growth with real ownership and global impact. Versátil work model with 100% remote or hybrid options. (Remote contracts available in Spain, Italy, UK, Belgium, Netherlands, France, and Germany.) Home office setup budget up to €1,000

📌 Senior PHP Software Engineer (Comunidad de Madrid)
🏢 Seedtag
📍 Comunidad de Madrid