👉 Senior/ Principal Frontend Developer (React)

The leading browser used by millions of users worldwide, with over 30 years of driving web innovation. We continue to deliver fast, secure, and reliable technology, and we’re now building the next generation of the browser experience. Join us as a Senior/ Principal Frontend Developer and help shape the future of the web.

🟣 You will be:

• contributing to the development of core browser features used by millions of users around the world,

• working directly with modern Web APIs (DOM, Fetch, Web Storage, Web Workers) and pushing the boundaries of what the frontend can do,

• designing and building new functionalities with React (18/19) and TypeScript,

• analyzing and improving performance, caching strategy, and overall application architecture,

• collaborating with backend engineers and product teams to design efficient client–server communication,

• proposing and selecting solutions based on architectural drivers and trade-offs,

• ensuring clean architecture, code quality, and maintainability through best practices and code reviews,

• debugging complex issues using deep knowledge of JavaScript internals and browser behavior,

• taking a holistic view of the system — identifying how different components influence performance, security, and user experience,

• occasionally helping refine internal standards, development tools, and engineering processes.

🟣 Your profile:

• excellent knowledge of JavaScript (ES6+) with deep understanding of: event loop, hoisting, variable scoping, closures, event bubbling/capturing, prototype chain & inheritance, promises and async/await,

• strong understanding of different data structures (Set, Map, WeakMap, etc.) and when to use them,

• practical and conscious use of TypeScript, understanding both its strengths and limitations,

• hands-on experience with React 18/19,

• solid knowledge of Web API ecosystem, including DOM API, Fetch API, Web Storage API, Web Workers,

• very good understanding of REST architecture and client–server communication, including headers and caching,

• awareness of differences between REST, GraphQL, and other API architectures,

• understanding of caching layers, strategies, and their impact on performance,

• strong debugging and analytical skills,

• good grasp of general programming principles, enabling flexibility across languages and paradigms,

• strong understanding of code design principles, quality standards, and ways to evaluate code health,

• knowledge of algorithmic fundamentals and ability to reason about complexity in practice,

• excellent understanding of the frontend ecosystem — networking, browser mechanics, performance, and security.

Work from the European Union region and a work permit are required.

🟣 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.