We’re looking for a Fullstack Engineer - Ad Serving 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 Fullstack Engineer - Ad Serving AdExchange, you will:

• High-Performance Ad Tags: Optimize our "Ad Tags" (Typescript) to ensure seamless rendering across millions of pages. You will deal with cross-browser compatibility, DOM manipulation, and the Critical Rendering Path where every millisecond counts.

• SaaS & Design Systems: Lead the evolution of our Curation tools using a robust, scalable Design System to ensure a top-tier UX.

• Fullstack Ownership: Work closely with backend engineers to contribute to the Node.js services. You will help design the APIs that feed our tags, ensuring they are as lean and fast as possible.

• Scalable Architecture: Help us implement DDD (Domain-Driven Design) and Event-Driven patterns. We value your frontend expertise here to ensure our APIs are as developer-friendly as they are fast.
  
  

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

• Frontend: Typescript, React, Styled Components / Design Systems.

• Client-Side: High-performance Vanilla JS/TS (Ad Tags).

• Backend (Where you'll grow): Node.js, Go, Microservices.

• Infrastructure: Kubernetes, Kafka, Redis.
  
  

What You’ll Need to Succeed

• Browser Internals Mastery: You have 5+ years of experience with TypeScript and deep knowledge of how browsers work (Event Loop, DOM, Web APIs, Security/Sandboxing).

• The Ad Serving Mindset: You understand that "Frontend" in Adtech means building small, highly-optimized scripts that run on other people's websites without breaking them.

• The Fullstack "Predisposition": You aren't just a UI developer. You have a strong interest in the backend (Node.js). You view the server as the natural extension of the client.

• SaaS & Design Systems: You have experience building complex B2B platforms where consistency, reusability, and performance are paramount.

• Software Craftsmanship: You advocate for Clean Code and SOLID principles. You believe that "done" includes being well-tested, documented, and observable.

• Adaptability: You are excited by the idea of moving across the stack. You see the backend as an opportunity to broaden your impact rather than a chore.

• Architecture Awareness: Even if your primary strength is in the client, you understand the principles of building scalable systems. You appreciate why we use Hexagonal Architecture or Clean Architecture to separate business logic from the delivery mechanism. You have a solid grasp in DDD and Event-Driven Architectures to design resilient APIs.

• AI-Augmented Productivity: You embrace AI tools (GitHub Copilot, Claude code, LLMs, etc.) as a fundamental part of your daily workflow. You understand how to leverage these tools to speed up boilerplate coding, debugging, and learning, allowing you to focus on high-level architecture and complex problem-solving.
  
  

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.