Location: Poland (Remote/Flexible) We are: RTB House is a global company that provides state-of-the-art marketing technologies for top brands and agencies worldwide. Its proprietary ad-buying engine is the first in the world to be powered entirely by Deep Learning algorithms, enabling advertisers to generate outstanding results and reach their goals at every stage of the funnel. We are looking for engineers to join our Bidding Platform organization which is the core of the RTB business, processing over 20 million requests per second to participate in real-time auctions and display advertisements to customers from 90+ countries. If you want to work on technically complex and demanding solutions, this is the opportunity for you! Our Senior Engineers are experts who combine deep technical expertise with a strong sense of ownership, and they take on Tech Lead roles in complex, cross-team projects. You will: Gain deep understanding our ad technology and become familiar with ad industry standards: OpenRTB, MRAID, VAST etc. Design and lead implementation of high-quality frontend solutions for displaying Ads globally, focusing on performance and scalability. Write, test, and deploy robust, efficient, and well-documented code in JavaScript/TypeScript, ensuring adherence to the highest coding standards. Develop monitoring systems to track crucial metrics like reliability or viewability and use data to diagnose and resolve performance bottlenecks. Collaborate closely with Ads Layouts specialists and backend engineers to ensure smooth data flow and optimal architectural alignment for performance-critical features. Provide hands-on technical leadership: solving complex system challenges, participating in planning and scoping of projects, and ensuring the implementation of the highest coding standards through participation in code reviews. Requirements: 8+ years of hands-on experience in developing complex web software Proficiency in JavaScript/TypeScript and browser APIs. Experience with relevant build tooling (e.g., Webpack, Vite). Practical experience and strong understanding of Web Performance optimization techniques and advanced loading strategies (caching, asset delivery). Very good knowledge of fundamental Internet protocols and technologies (DNS, HTTP, cookies and others). Practical ability to observe, monitor and analyse the operation of production systems (and draw valuable conclusions from it). Good understanding of full-stack concepts, including system architectures, working with backend APIs and deployment/CI/CD pipelines. C1 level in English and Polish. Nice to have: Experience in the AdTech/Real Time Bidding space. Experience contributing to Real User Monitoring (RUM) systems. We Offer: Projects focused on extreme performance and high code quality – clean code and solid code reviews are our standard. Collaboration within an interdisciplinary, self-sufficient team (including DevOps, database experts, backend developers, product designers, and QA engineers). Access to modern technologies and the opportunity to apply them in large-scale, high-impact projects. Cooperation based on B2B contract. You can cooperate 100 % remotely or choose one of our office spaces in Warsaw or Cracow. You don't need to tick every box to apply. If you are passionate about software engineering, send us your CV, and we'll review it.