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# Senior Software Engineer

- **Company:** Seedtag
- **Location:** Madrid, Spain (Remote available)
- **Contract:** Permanent contract
- **Skills:** Application Programming Interfaces (APIs), Artificial Intelligence, Big Data, Cloud Computing, Distributed Systems, Python (Programming Language), Machine Learning, Node.Js, Software Maintenance, TypeScript, Retrieval-Augmented Generation, Large Language Models, Backend, Terraform, Data Pipelines, Golang, Microservices
- **Published:** October 20, 2026
- **Apply:** https://www.indeed.com/viewjob?jk=81051423a624d5c3

## About the Role

* Strong hands-on Golang experience, building and maintaining backend services in production.
 * Solid understanding of distributed systems, particularly high-throughput or low-latency architectures.
 * Hands-on experience with LLM APIs, embeddings, or RAG, alongside a strong interest in AI technologies.
 * Experience with cloud infrastructure, observability, and production system monitoring.
 * Familiarity with Infrastructure as Code principles and tools.
 * Strong problem-solving skills and a pragmatic approach to delivering reliable, maintainable software.
 * Ability to work autonomously, adapt to changing priorities, and collaborate effectively with technical and non-technical stakeholders., * Have experience with Python, Node.js, or TypeScript.
 * Have worked in AdTech, particularly with RTB, OpenRTB, or CTV.
 * Have experience processing large-scale data or building real-time advertising systems.

## Description

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.
 * AI & ML Integration: 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.
 * Platform Evolution: 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.
 * Engineering Excellence: Write clean, maintainable code while balancing quality, speed, and evolving business priorities., You'll work with technologies supporting Seedtag's scalable backend systems and AI-powered capabilities.

Our stack includes:

 * Core Language: Go / Golang.
 * Additional Languages: Python, Node.js, TypeScript.
 * Architecture: Distributed systems, microservices, high-throughput and low-latency services, APIs.
 * AI & Machine Learning: LLM APIs, embeddings, RAG, ML model integration.
 * Infrastructure & Observability: Cloud infrastructure, monitoring, Infrastructure as Code (e.g. Terraform).
 * Domain: OpenWeb, CTV, in-app contextualisation, RTB.