Fullstack Engineer - Ad Serving AdExchange
Role details
Job location
Tech stack
Job description
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.
Requirements
Do you have experience in TypeScript?, * 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.
Benefits & conditions
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A key moment of growth with real ownership and global impact.
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Flexible work model with 100% remote or hybrid options. (Remote contracts available in Spain, Italy, UK, Belgium, Netherlands, France, and Germany.)
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Continuous learning through a learning platform and optional language classes.
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A supportive, trust-based culture that values well-being.
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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.
