Backend Software Engineer - AdExchange

You will architect, refine and develop the backend services that power our AdExchange. In an industry where milliseconds determine success, you will focus on:

• Optimizing high-throughput real-time bidding systems while balancing ultra-low latency, cost efficiency and reliability.
• Integrating new demand partners and owning the full lifecycle from capacity planning and endpoint configuration to traffic shaping and performance validation.
• Designing pricing and auction mechanics including bid flooring systems and dynamic margin calculations, serving machine learning models in real time to optimize revenue.
• Building event pipelines and reporting integrations so data teams can analyze performance, debug issues and feed AI models.
• Working on end-to-end projects from concept to production, making technical decisions, managing priorities and communicating with stakeholders across the company.
• Collaborating with cross-functional teams with a data-driven mindset, validating hypotheses with real data and aligning engineering work with business goals.

This is a high-impact challenge that will help shape the future of Seedtag., Outcome over output We focus on solving meaningful problems and delivering results that create real impact for customers.

Failure is allowed, learning is a must We test early, iterate continuously and treat failures as opportunities to learn and improve.

We leave things better than we found them Engineers take ownership and actively improve systems and processes.

We are data-driven Engineering decisions are guided by data and continuous system monitoring.

How we work

Our backend stack includes:

• Go
• Typescript
• Python
• MongoDB
• Redis
• Google Cloud
• Kafka

We build:

• High-throughput microservices
• APIs
• Data pipelines
• Asynchronous message queues

Engineering practices include:

• DevOps culture
• Kanban workflows
• Pair programming
• Peer reviews
• Continuous discovery, delivery and integration

Collaboration tools:

• Slack
• Notion
• Jira
• GitHub

Do you have experience in TypeScript?, * You have a strong understanding of backend development and at least 5 years of experience building backend systems.

• You write maintainable code and apply solid programming practices and design patterns.
• You have experience with high-throughput systems and distributed architectures that handle large volumes of data.
• You use AI tools (such as GitHub Copilot, Claude Code or other LLMs) to improve productivity in coding, debugging and learning.
• You understand both the technical and business context of the projects you work on.
• You enjoy solving complex technical problems and building creative solutions.
• You continuously learn and stay up to date with backend engineering developments.
• You communicate effectively and collaborate well with both technical and non-technical stakeholders.

• Unlimited work from home
• Strong work-life balance
• Inclusive and supportive work environment
• Latest MacBook Pro and €1,000 for home office setup
• Mentoring and career development with learning budget
• Restaurant, transport and childcare benefits
• Medical insurance discounts

Additional benefits:

• Free English, Spanish and French lessons
• Paid travel to the Madrid headquarters to meet teams
• Paid offsite team events and Christmas events
• "One Seedtag" program: work for one month from another Seedtag office with travel and accommodation covered

Our goal is to promote a better advertising industry where effective ads respect the user's privacy and experience. 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 more than 700 employees across 17 countries, backed by €250M in funding, and operates today as a global ad-tech leader. What scale? In numbers: * We handle more than 240 billion events per day * We process on average 800,000 web pages per hour * Our CDN serves 1.5 petabytes every month to 300 million devices worldwide, Seedtag is one of the fastest growing startups in Europe, working on large-scale engineering challenges in the advertising technology industry.