We’re looking for a Backend Engineer - AdExchange to join our tech team and help build the future of neuro-contextual advertising at global scale.

Who We Are

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 700+ 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.

Your Challenge

As a Backend Engineer - AdExchange, you’ll build systems that categorize global ad inventory and enrich bidding requests with real-time contextual data, helping improve auction performance and revenue through experimentation and iteration.

• Inventory & Bid Enrichment: Own the core services that manage our global ad inventory and enrich bids with contextual metadata. This is a critical "hot path" in our infrastructure where low latency is non-negotiable.

• High-Performance Node.js: Utilise Node.js, TypeScript, and Fastify to build ultra-low-latency services capable of handling hundreds of millions of requests daily.

• Architectural Excellence: Lead the way in applying Hexagonal Architecture and Domain-Driven Design (DDD) to ensure our AdExchange remains maintainable and scalable as we grow.

• Event-Driven Systems: Design and evolve our data pipelines using Kafka, ensuring that bid enrichment and inventory updates are processed reliably and asynchronously.

• Technical Ownership: You will be responsible for making key technical decisions, managing project timelines, and collaborating with Data and Product teams to drive the project forward.

• Quality & Observability: Ensure our services are not only fast but also resilient, well-tested, and fully observable through robust monitoring and logging practices.
  
  

Our Core Values

Outcome over Output
We measure success by impact and value, not by volume of features or lines of code.

Failure Is Allowed, Learning Is a Must
Experimentation is key to innovation. We test early, iterate often, and learn fast.

We Are All Scouts
We take ownership and leave things better than we found them.

We Are Data-Driven
Data informs our decisions and helps us continuously improve our systems and results.

Tech Stack

• Primary: Node.js, TypeScript, Fastify.

• Secondary: Go (Golang).

• Data & Messaging: Kafka, MongoDB, Redis.

• Infrastructure: Kubernetes, AWS, Terraform.

• Patterns: DDD, Hexagonal Architecture, Event-Driven Microservices.
  
  

What You’ll Need to Succeed

• 5+ years in backend engineering, building reliable and high-performance systems.

• Strong Node.js & TypeScript skills, with solid knowledge of async programming (Fastify is a plus).

• Hands-on with modern architectures, especially Hexagonal Architecture and DDD.

• Experience with distributed systems, event-driven architectures, and tools like Kafka.

• Product mindset, understanding business impact and balancing quality with delivery.

• AI-friendly engineer, using AI tools to work smarter and improve development workflows.

• Passion for clean code, applying SOLID principles and testing practices like TDD.

• Interest in Go (Golang) and willingness to contribute when needed.

Why Join Seedtag?

• A key moment of growth with real ownership and global impact.

• Flexible work model with 100% remote or hybrid options.
  (Remote contracts available in Spain, Italy, UK, Belgium, Netherlands, France, and Germany.)

• Continuous learning through a learning platform and optional language classes.

• A supportive, trust-based culture that values well-being.

• Team activities, offsites, and opportunities to connect beyond work.
  
  

Additional Perks

• Home office setup budget up to €1,000

• Paid trips to our HQ in Madrid

• MacBook Pro M3
  
  

Ready to Join the Seedtag Adventure?

At Seedtag, we create an environment where everyone can thrive. If you need accommodations during the hiring process, let us know and we’ll ensure a positive experience.

Send us your CV and let’s build the future of neuro-contextual advertising together.