Senior JavaScript Engineer (m/f/d) – Focus on Web Performance & SDK

We are an established, profitable company in the privacy and adtech space - helping publishers and media houses across Europe offer cross-publisher monetization models. Our technology powers multiple billion page impressions every month, and we’re scaling fast into new markets. We combine the best of both worlds: the stability of a profitable business and the agility and ownership mindset of a startup. Every team member has a visible impact and we encourage you to shape not just our products but also our culture.

We are looking for a Senior Software Engineer to take ownership of our SDK - the core component integrated into partner websites. This SDK manages communication with CMPs (Consent Management Platforms) and our stack, ensuring privacy compliance, performance, and reliability at scale. You’ll be responsible for evolving the SDK into a high-performance, secure, and extensible framework that can:

• Integrate with additional CMPs
• Unlock access to premium content models
• Potentially detect and block 3rd-party requests, ads, and trackers

This role is ideal for an engineer who thrives at the intersection of web performance, browser internals, and privacy technology - someone who takes pride in writing elegant, efficient, and secure TypeScript code.

What You'll Do

• Own the design, development, and evolution of our web SDK used across publisher integrations.
• Ensure high performance, reliability and scalability for billions of monthly impressions.
• Work closely with the whole engineering and product teams to extend SDK functionality for new CMPs and features.
• Debug complex browser and integration issues across different environments.
• Champion best practices for security, maintainability and developer experience.
• Collaborate cross-functionally with other engineers and stakeholders to ship improvements quickly.

Required Skills & Experience

• 5+ years of professional software engineering experience.
• Deep understanding of JavaScript/TypeScript and modern web APIs.
• Strong experience debugging in complex, cross-browser environments.
• Solid understanding of browser networking, cookies, privacy and security mechanisms.
• Experience building SDKs, libraries or embeddable scripts at scale.
• Excellent communication skills and ownership mindset - you ship and iterate fast.
• You care about understanding how things work and improving them, not just completing tasks.
• Strong English communication skills in written and verbal communication - you thrive in explaining technical challenges to your peers.

Mindset

• Intrinsic motivation - you care about why, not just what.
• Curiosity and eagerness to learn - you stay up-to-date with technology trends and share it with the team.
• Ownership mentality - you take responsibility and follow through.
• Pragmatic problem-solver - you value clarity, simplicity, and maintainability.
• Product-focused thinking - you consider the real-world context and user impact behind the code.

Nice-to-Have

• Familiarity with privacy tech, adtech, or CMP integrations.
• Experience with APIs and caching layers.
• Familiarity with Node.js and modern CI/CD environments.
• Interest in performance profiling, browser automation or content blocking.

Why You’ll Love Working Here

• Impact: Your work directly affects billions of web requests monthly and that makes you proud.
• Ownership: Take the lead on a mission-critical SDK with real autonomy.
• Flexibility: Remote-first culture, flexible working hours and async-friendly communication.
• Growth: Be part of a profitable, scaling company entering new markets.
• Equity Upside: Participate in our beneficiary share program.
• Culture: A collaborative, fast-moving team where new ideas are encouraged and deployed fast.