Senior Full Stack/Web Performance Engineer

🏢 Summary: Senior-level role focused on designing and leading high-performance, scalable frontend and full-stack solutions for global ad delivery and tracking systems. The position emphasizes web performance optimization, observability (RUM and Synthetic), and architectural excellence across performance-critical features. You will drive measurable improvements in user metrics while maintaining top coding standards and technical leadership. 🗂️ Requirements: 8+ years of hands-on software engineering experience, Strong understanding of frontend development and internal mechanisms, Proven experience in web performance optimization and advanced loading strategies, Proficiency in JavaScript and TypeScript, Experience with modern frontend frameworks (React), Experience with build tools (Webpack or Vite), Knowledge of Internet protocols and technologies (DNS, HTTP, cookies), Experience monitoring and analyzing production systems, Understanding of full-stack concepts and backend APIs (Node.js, Python, or Java), Experience with deployment and CI/CD pipelines 📃 Skills: JavaScript, TypeScript, React, Node.js, Python, Java, Webpack, Vite, DNS, HTTP, Cookies, RUM, Synthetic, CICD, Caching, Monitoring 🏢 Description: You will: Design and lead implementation of system changes that deliver high performance, scalability and observability for displaying and tracking ads world wide. Develop tools and optimizations to drive measurable improvements in critical user performance metrics. Implement and maintain high-quality frontend and full-stack solutions for displaying Ads globally, focusing on extreme performance and scalability. Develop monitoring systems (RUM and Synthetic) 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. Write, test, and deploy robust, efficient, and well-documented code in JavaScript/TypeScript/Python/Java, ensuring adherence to the highest coding and performance standards. 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 software engineering, including the understanding of Frontend Development and its internal mechanisms. Practical experience and strong understanding of Web Performance optimization techniques and advanced loading strategies (caching, asset delivery). Solid proficiency in JavaScript/TypeScript and modern frameworks like e.g., React. Experience with relevant build tooling (e.g., Webpack, Vite). 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 working with backend APIs (Node.js, Python, or Java) 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. Selected technologies used: You will be working within a modern stack that includes JavaScript/TypeScript, React, Node.js, Python, and Java. We Offer: Projects focused on extreme performance and high code quality – solid code reviews are our standard. Collaboration within an interdisciplinary, self-sufficient team (including DevOps, database experts, backend developers, product designers, and QA engineers). Hardware and software tailored to your preferences (e.g., MacBook, AI tool licenses). Flexible working conditions – no core hours, fully remote cooperation possible. Apply now! You don't need to tick every box to apply. If you are passionate about software engineering or web performance, send us your CV, and we'll review it.

🏢 Summary: Senior engineer role focused on designing and implementing high‑performance, scalable frontend and full‑stack solutions for global ad delivery systems. The position emphasizes web performance optimization, observability, and monitoring (RUM and Synthetic) to improve critical user metrics. You will lead technical initiatives, build performance‑critical features, and ensure high code quality across JavaScript/TypeScript-based systems. 🗂️ Requirements: 8+ years of hands-on software engineering experience, Strong understanding of frontend development and internal browser mechanisms, Practical experience with web performance optimization techniques, Proficiency in JavaScript and TypeScript, Experience with modern frontend frameworks (React), Experience with build tools (Webpack or Vite), Knowledge of Internet protocols (DNS, HTTP, cookies), Experience monitoring and analyzing production systems, Understanding of full-stack architecture and backend APIs (Node.js, Python, or Java), Experience with CI/CD pipelines 📃 Skills: JavaScript, TypeScript, React, Node.js, Python, Java, Webpack, Vite, DNS, HTTP, cookies, CI/CD, RUM, Synthetic, caching, observability, APIs 🏢 Description: You will: Design and lead implementation of system changes that deliver high performance, scalability and observability for displaying and tracking ads world wide. Develop tools and optimizations to drive measurable improvements in critical user performance metrics. Implement and maintain high-quality frontend and full-stack solutions for displaying Ads globally, focusing on extreme performance and scalability. Develop monitoring systems (RUM and Synthetic) 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. Write, test, and deploy robust, efficient, and well-documented code in JavaScript/TypeScript/Python/Java, ensuring adherence to the highest coding and performance standards. 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 software engineering, including the understanding of Frontend Development and its internal mechanisms. Practical experience and strong understanding of Web Performance optimization techniques and advanced loading strategies (caching, asset delivery). Solid proficiency in JavaScript/TypeScript and modern frameworks like e.g., React. Experience with relevant build tooling (e.g., Webpack, Vite). 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 working with backend APIs (Node.js, Python, or Java) 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. Selected technologies used: You will be working within a modern stack that includes JavaScript/TypeScript, React, Node.js, Python, and Java. We Offer: Projects focused on extreme performance and high code quality – solid code reviews are our standard. Collaboration within an interdisciplinary, self-sufficient team (including DevOps, database experts, backend developers, product designers, and QA engineers). Hardware and software tailored to your preferences (e.g., MacBook, AI tool licenses). Flexible working conditions – no core hours, fully remote cooperation possible. Apply now! You don't need to tick every box to apply. If you are passionate about software engineering or web performance, send us your CV, and we'll review it.

🏢 Summary: Design and lead the implementation of high-performance, scalable and observable systems for global ad serving and tracking. The role focuses on building and optimizing HTTP/gRPC services and batch jobs in Java and Python, ensuring production reliability and measurable performance improvements. You will provide hands-on technical leadership while maintaining high engineering and code quality standards. 🗂️ Requirements: Strong knowledge of Java and Python, Experience building and maintaining HTTP and gRPC services, Experience with batch processing systems, Understanding of distributed systems and concurrency, Knowledge of Internet protocols (DNS, HTTP, cookies), Ability to design for high scalability and high availability, Experience monitoring and analyzing production systems, Ability to optimize system performance at scale, Experience deploying and maintaining production environments, Understanding of complex systems from hardware to algorithms 📃 Skills: Java, Python, HTTP, gRPC, DNS, Aerospike, Memcached, GCP, BigQuery, MinIO, Kafka, Clickhouse, PostgreSQL, Elasticsearch, Kubernetes, Prometheus, Jenkins, Graphite, Concurrency, DistributedSystems, Scalability, Availability, Monitoring, Performance 🏢 Description: You will: Design and lead implementation of system changes that deliver high performance, scalability and observability for displaying and tracking ads world wide. Develop tools and optimizations to drive measurable improvements in critical user performance metrics. Implement, test, deploy, monitor and maintain (in all aspects, including setting up environment, writing configuration code, monitor production) HTTP / gRPC services and batch jobs in Java and Python, ensuring adherence to the high engineering standards. 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. Desired experience: Excellent understanding of how complex IT systems work - from the hardware level, through software, to algorithms. Very good knowledge of fundamental Internet protocols and technologies (DNS, HTTP, cookies and others). Good knowledge of basic methods of creating concurrent programs and distributed systems (from thread level to geo-distributed clusters level). Practical ability to observe, monitor and analyse the operation of production systems (and draw valuable conclusions from it). The ability to critically analyze the solutions created in terms of performance (from estimating the theoretical performance of the designed systems to detecting and removing actual performance problems in production). General knowledge of issues (typical problems and methods of solving them) in the areas of 'high scalability' and 'high availability'. 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. Selected technologies used: Java, Python Aerospike, Memcached Google Cloud Platform, BigQuery, MinIO Kafka, Clickhouse PostgreSQL Elasticsearch Kubernetes, Prometheus Jenkins, Graphite We Offer: Projects focused on extreme performance and high code quality – solid code reviews are our standard. Collaboration within an interdisciplinary, self-sufficient team (including DevOps, database experts, backend developers, product designers, and QA engineers). Hardware and software tailored to your preferences (e.g., MacBook, AI tool licenses). Flexible working conditions – no core hours, fully remote cooperation possible. Apply now! 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.

🏢 Summary: Design and lead the implementation of highly scalable, high‑performance ad serving and tracking systems, building and optimizing HTTP/gRPC services and batch jobs in Java and Python. The role combines hands-on development with technical leadership, focusing on observability, reliability, and measurable performance improvements in distributed production environments. You will work on globally distributed systems handling large-scale traffic with strong engineering and code quality standards. 🗂️ Requirements: Experience designing and implementing high-performance, scalable distributed systems, Strong knowledge of Java and Python, Experience building and maintaining HTTP and gRPC services, Understanding of Internet protocols (DNS, HTTP, cookies), Knowledge of concurrency and distributed systems concepts, Ability to monitor, analyze and optimize production systems, Experience with high scalability and high availability architectures, Fluent English and Polish (C1) 📃 Skills: Java, Python, HTTP, gRPC, DNS, Aerospike, Memcached, GCP, BigQuery, MinIO, Kafka, Clickhouse, PostgreSQL, Elasticsearch, Kubernetes, Prometheus, Jenkins, Graphite 🏢 Description: You will: Design and lead implementation of system changes that deliver high performance, scalability and observability for displaying and tracking ads world wide. Develop tools and optimizations to drive measurable improvements in critical user performance metrics. Implement, test, deploy, monitor and maintain (in all aspects, including setting up environment, writing configuration code, monitor production) HTTP / gRPC services and batch jobs in Java and Python, ensuring adherence to the high engineering standards. 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. Desired experience: Excellent understanding of how complex IT systems work - from the hardware level, through software, to algorithms. Very good knowledge of fundamental Internet protocols and technologies (DNS, HTTP, cookies and others). Good knowledge of basic methods of creating concurrent programs and distributed systems (from thread level to geo-distributed clusters level). Practical ability to observe, monitor and analyse the operation of production systems (and draw valuable conclusions from it). The ability to critically analyze the solutions created in terms of performance (from estimating the theoretical performance of the designed systems to detecting and removing actual performance problems in production). General knowledge of issues (typical problems and methods of solving them) in the areas of 'high scalability' and 'high availability'. 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. Selected technologies used: Java, Python Aerospike, Memcached Google Cloud Platform, BigQuery, MinIO Kafka, Clickhouse PostgreSQL Elasticsearch Kubernetes, Prometheus Jenkins, Graphite We Offer: Projects focused on extreme performance and high code quality – solid code reviews are our standard. Collaboration within an interdisciplinary, self-sufficient team (including DevOps, database experts, backend developers, product designers, and QA engineers). Hardware and software tailored to your preferences (e.g., MacBook, AI tool licenses). Flexible working conditions – no core hours, fully remote cooperation possible. Apply now! 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.

🏢 Summary: The offer is for a software engineer role focused on designing and optimizing high-performance, low-latency systems handling over 24 million queries per second. The position involves building scalable and reliable distributed components, improving performance, and developing monitoring and testing tools in a production environment. The role emphasizes high availability, scalability, and working with modern cloud and data technologies. 🗂️ Requirements: Proficiency in programming, Strong understanding of complex IT systems from hardware to algorithms, Knowledge of Internet protocols (DNS, HTTP, cookies), Knowledge of concurrent programming and distributed systems, Experience with monitoring and analyzing production systems, Ability to optimize system performance and resolve performance issues, Knowledge of high scalability and high availability concepts, C1 level English, C1 level Polish 📃 Skills: Java, Python, Aerospike, Memcached, GCP, BigQuery, MinIO, Kafka, Clickhouse, PostgreSQL, Elasticsearch, Kubernetes, Prometheus, Jenkins, Graphite, DNS, HTTP 🏢 Description: You Will: Design and programming of a wide range of modules and components as part of a system that supports over 24M queries per second and low latency. Work on the optimization of the developed software in terms of response time and resource consumption Ensure the reliability and scalability of the solutions built Create performance and correctness tests for new system components Analyse new technologies in terms of their applicability in production conditions Develop tools for monitoring and analysing the operation of the production system Continuous optimization of existing tools and processes Desired Experience: Proficiency in programming Excellent understanding of how complex IT systems work (from the hardware level, through software, to algorithmics) Very good knowledge of fundamental Internet protocols and technologies (DNS, HTTP, cookies and others) Good knowledge of basic methods of creating concurrent programs and distributed systems (from thread level to continent level) Practical ability to observe, monitor and analyse the operation of production systems (and draw valuable conclusions from it) The ability to critically analyze the solutions created in terms of performance (from estimating the theoretical performance of the designed systems to detecting and removing actual performance problems in production) General knowledge of issues (typical problems and methods of solving them) in the areas of 'high scalability' and 'high availability' C1 level in English and Polish Selected Technologies: Java, Python Aerospike, Memcached Google Cloud Platform, BigQuery, MinIO Kafka, Clickhouse PostgreSQL Elasticsearch Kubernetes, Prometheus Jenkins, Graphite 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. Apply now! You don't need to tick every box to apply. If you are passionate about digital marketing, send us your CV, and we'll review it.

🏢 Summary: Senior Web Architect role focused on driving technical optimization, architectural governance, and web performance across multiple development teams. The position involves evaluating and integrating modern front-end technologies within a MACH/microservices landscape while reducing technical debt and ensuring best development practices. You will coordinate architectural decisions and guide teams in building scalable, high-performance web solutions. 🗂️ Requirements: Minimum 5 years web development experience, Minimum 3 years architecture experience, Strong knowledge of MACH architecture, Strong knowledge of Microservices architecture, Deep expertise in Next.js, Deep expertise in NodeJS, Deep expertise in TypeScript, Experience with GitHubActions, Experience with GraphQL, Experience with Git, Strong understanding of Webperformance, Ability to evaluate and implement technical optimizations, Experience coordinating architectural decisions (ADRs), Fluent English 📃 Skills: Next.js, NodeJS, TypeScript, GraphQL, Git, GitHubActions, MACH, Microservices, Kubernetes, ContentStack, commercetools, Webperformance, Architecture, AI 🏢 Description: Your responsibilities Investigate technical optimizations, synergies, automation (ex: through AI), and technical depth / debt reduction potential. Coordinate processes, decisions and patterns of development across seven development teams (ex: facilitate architectural decision records ADRs) Evaluates front-end technical concepts and technologies for feasibility and fit-check into the system landscape (proof of concepts, technology review and critical analysis). Steer & consult the practices defined in the project, and regarding web performance and review the overall development practices with the teams, starting from benchmarking and metrics definitions etc. Your profile Min 5 years experience in the field of web development (overall). Min 3 years experience in architecture related areas. Higher education (Bachelor or Master) in computer science or related fields is preferable, however this is optional in case other significant credentials in experience and knowledge can be demonstrated (certificates / long experience with successful track record / references). Familiar and comfortable with modern software development principles, practices and frameworks (specifically MACH / Microservices architecture). Deep understanding in: Next.js, NodeJS, TypeScript, Github actions, GraphQL, Git, Web performance. Familiarity that are nice to have: Kubernetes, CMS Systems (ContentStack), Commerce systems (commercetools). Fluent and comfortable in English. Great communication skills are essential (collaboration cross-teams, locations and stakeholders is the core of this role). Your benefits Dynamic International Environment: Collaborate with diverse teams globally, enriching your experience and expanding your professional network Collaborative Team Culture: Join a supportive team that values your contributions and encourages your growth Professional Development Opportunities: Expand your skills through engaging projects and responsibilities that challenge and inspire you Flexible hybrid work arrangements: Enjoy a mix of remote work and office collaboration, with a minimum of one day per week in our modern offices Comprehensive Benefits Package: Enjoy private health care, a Lunchpass card, a sports card, group insurance options and employee discounts

🏢 Summary: Senior Frontend Engineer role focused on designing and leading high-performance ad display solutions within a large-scale real-time bidding platform processing millions of requests per second. The position combines hands-on development in JavaScript/TypeScript with technical leadership in complex, cross-team projects. Work centers on performance optimization, scalability, and production system monitoring in a global AdTech environment. 🗂️ Requirements: 8+ years of experience developing complex web software, Proficiency in JavaScript and TypeScript, Strong knowledge of browser APIs, Experience with build tools such as Webpack or Vite, Practical experience with web performance optimization and advanced loading strategies, Very good knowledge of DNS, HTTP, cookies and related Internet technologies, Ability to monitor, analyze and troubleshoot production systems, Understanding of system architectures and backend API integration, Experience with CI/CD pipelines 📃 Skills: JavaScript, TypeScript, BrowserAPIs, Webpack, Vite, OpenRTB, MRAID, VAST, DNS, HTTP, Cookies, CI/CD, Monitoring, RUM, APIs, Caching 🏢 Description: 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.

🏢 Summary: The role involves developing and maintaining high-performance backend systems for advertising and e-commerce platforms, focusing on scalable microservices and real-time data processing using Kotlin and Spring Boot. You will design low-latency services, contribute to system architecture, and support production environments in a high-scale setting. The position also emphasizes AI-assisted development practices and collaboration within engineering teams. 🗂️ Requirements: 3+ years of backend development experience, Very good knowledge of Kotlin, Very good knowledge of Spring Boot, Hands-on experience with microservices architecture, Experience with NoSQL databases, Experience with MongoDB, Experience building and maintaining backend systems and APIs, Understanding of system design and scalable architecture, Experience with high-performance and high-scale systems, English B2 level, Polish C1 level, Work permit in the European Union, Openness to occasional visits to Warsaw office, Experience using AI-powered coding assistants 📃 Skills: Kotlin, SpringBoot, MongoDB, NoSQL, Microservices, REST, APIs, GenAI, Claude, GitHubCopilot, Cursor, AWS, Azure 🏢 Description: 🟣 You will be: developing and maintaining backend systems for advertising and e-commerce platforms, building low-latency, high-performance services processing large volumes of data, developing scalable microservices and APIs using Kotlin and Spring Boot, working on real-time event processing and advertising targeting mechanisms, contributing to architecture design and system scalability improvements, collaborating with stakeholders and supporting engineering best practices, including code reviews and code quality standards, participating in technical readiness/on-call support for production incidents a few days per month. 🟣 Your profile: 3+ years of professional experience in backend development, very good knowledge of Kotlin and Spring Boot, openness to occasional visits to the Warsaw office (1–2 days per quarter), hands-on experience with microservices architecture, practical experience working with NoSQL databases, especially MongoDB, experience building and maintaining backend systems and APIs, understanding of system design and scalable architecture principles, experience working with high-performance and high-scale systems, strong analytical thinking and problem-solving skills, ability to collaborate effectively with stakeholders and engineering teams, good communication skills in English (B2) and Polish (C1), practical experience using AI-powered assistants (e.g. Claude Code, GitHub Copilot, Cursor) to improve productivity, quality, or decision-making in software delivery. Work from the European Union region and a work permit are required. 🟣 Nice to have: experience applying GenAI in a more structured way within the SDLC, including defined workflows, prompt patterns, or tool integrations embedded into daily work, interest in and familiarity with emerging AI-driven practices (e.g. agent-based workflows, automation patterns, AI-augmented development), with a willingness to explore and experiment beyond standard approaches. 🟣 Recruitment Process: CV review – HR call – Technical Interview – Client Interview – Decision 🎁 Benefits 🎁 ✍ Development: development budgets of up to 6,800 PLN, we fund certifications e.g.: AWS, Azure, access to Udemy, O'Reilly (formerly Safari Books Online) and more, events and technology conferences, technology Guilds, internal training, Xebia Upskill. 🩺 We take care of your health: private medical healthcare, multiSport card - we subsidise a MultiSport card, mental Health Support. 🤸‍♂️ We are flexible: B2B or employment contract, contract for an indefinite period.

🏢 Summary: Senior Fullstack Engineer role focused on building intelligent advertising systems using React and Kotlin, including ML-driven recommendation engines and automated campaign management tools. The position involves developing scalable, event-driven cloud architectures and high-performance APIs for analytical platforms within a GCP environment. Hybrid work model in Warsaw with strong emphasis on modern microservices and microfrontend architectures. 🗂️ Requirements: Minimum 3 years of full-stack development experience, Strong experience with React and Kotlin, Proficiency in TypeScript, HTML, CSS, Experience with Spring Boot and microservices architecture, Experience with GCP cloud environment, Experience with MongoDB and SQL databases, Understanding of event-driven architectures and large-scale data processing, Experience with testing frameworks such as Jest, Vitest, or Playwright, Communicative Polish and English, Legal right to work in the European Union 📃 Skills: Kotlin, React, TypeScript, HTML, CSS, SpringBoot, MongoDB, SQL, GCP, Microservices, Microfrontends, Jest, Vitest, Playwright, APIs, SSR, Accessibility, EventDriven 🏢 Description: Unleash innovation — design the future of intelligent advertising ecosystems! Warszawa-based opportunity with hybrid work model. As a Senior Fullstack Engineer – React and Kotlin Specialists , you will be working for our client, a leader in building advanced advertising tools, focusing on creating intelligent recommendation systems and automating campaign management for advertisers on Allegro Ads. Join a mission-driven project that revolutionizes how businesses grow through cutting-edge technology and data-driven insights, offering exciting avenues for professional growth and innovation. Your main responsibilities: Develop and maintain backend services using Kotlin, integrating machine learning-driven recommendation engines in collaboration with data science teams. Build scalable, event-driven architectures to process large data volumes within cloud environments, leveraging GCP. Design and implement high-performance APIs to support analytical dashboards and market benchmarks. Create and optimize scalable microfrontends using React, prioritizing accessibility and server-side rendering for analytical tools. Collaborate with cross-functional teams to deliver seamless, secure, and efficient software solutions. Ensure high code quality through testing frameworks such as Jest, Vitest, or Playwright, with a focus on performance and reliability. Contribute to evolving microservice architectures, utilizing Spring Boot, MongoDB, SQL, and cloud-native tools. Participate actively in code reviews, sprint planning, and technical discussions to foster continuous improvement. You're ideal for this role if you have: At least 3 years of experience in full-stack development, with a focus on React and Kotlin. Strong proficiency in TypeScript, React, HTML/CSS, and backend technologies like Kotlin, Spring Boot, and microservices. Experience working with cloud ecosystems, preferably GCP. Solid understanding of database management, including MongoDB and SQL. Familiarity with event-driven architectures and large-scale data processing. Ability to communicate effectively in Polish and English. Experience working in an Agile environment with a focus on delivering high-quality software. It is a strong plus if you have: (optional) Certifications related to GCP or microservices architecture. Experience with agentic coding tools like Copilot/OpenCode. Knowledge of accessibility standards (a11y) and performance optimization techniques. Language Required for the role: Polish (Communicative) English (Communicative) Eligibility for this role: Only candidates with an existing legal right to work in the European Union will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior Frontend Developer role focused on building and leading high-performance frontend applications for self-serve advertising platforms in the AdTech domain. The project involves developing campaign management flows, pricing logic, and integrating programmatic components using modern JavaScript frameworks. Fully remote B2B contract for 6 months with possible extensions. 🗂️ Requirements: Proficiency in Nuxt (Vue 3), Strong TypeScript knowledge including Generics and Interfaces, Experience with Pinia state management, Knowledge of PrimeVue 4, Knowledge of Tailwind CSS, Familiarity with AJV or Zod validation libraries, Experience with dayjs and decimal.js, Experience with SSP/DSP or programmatic integrations, Experience with domain-driven architecture, Performance optimization skills 📃 Skills: Nuxt, Vue, TypeScript, Pinia, PrimeVue, Tailwind, AJV, Zod, dayjs, decimal.js, SSP, DSP, JavaScript, ESLint 🏢 Description: 🌍Work mode : remote. 💰 Rate: 140 -160 PLN/h on B2B. ⏰ Start : ASAP/ 1 msc. ⏳ Project length : 6 months + extensions. 📕Project language : English. ⚙️ Industry : AdTech. 💼 Workload : Full time. ⚙️ Recruitment process -1 technical interview. 💻 Equipment : work on own equipment. Summary: The role of the Senior Frontend Developer focuses on leading the development of high-performance frontend applications within the Ad-Tech domain , leveraging modern JavaScript frameworks . Main Responsibilities: Develop and maintain self-serve advertising platforms. Implement campaign management & booking flows. Actively contribute to pricing logic & financial calculations. Integrate SSP/DSP or programmatic components. Create and manage reporting & validation-heavy interfaces. Key Requirements: Proficient in Nuxt (Vue 3) . Strong command of TypeScript , including Generics and Interfaces. Experience with Pinia for state management. Knowledge of PrimeVue 4 and Tailwind CSS. Familiarity with AJV / Zod validation libraries. Skillful in dayjs & decimal.js . Experience with domain-driven architecture and performance optimization. Nice to Have: Experience with Nuxt Layers and modular architecture. Familiarity with the Mapper pattern (DTO → Domain). Experience with ESLint 9. Other Details: Work Environment: Remote position with significant flexibility in working hours. Industry: Engaging in a dynamic Ad-Tech landscape.