Senior/ Principal Frontend Developer (React)

Hello, let’s meet!

We are Xebia - a place where experts grow. For nearly two decades now, we've been developing digital solutions for clients from many industries and places across the globe. Among the brands we’ve worked with are UPS, McLaren, Aviva, Deloitte, and many, many more.

We're passionate about Cloud-based solutions. So much so, that we have a partnership with three of the largest Cloud providers in the business – Amazon Web Services (AWS), Microsoft Azure & Google Cloud Platform (GCP). We even became the first AWS Premier Consulting Partner in Poland.

Formerly we were known as PGS Software. In 2021, we joined Xebia Group – a family of interlinked companies driven by the desire to make a difference in the world of technology.

Xebia stands for innovation, talented team members, and technological excellence. Xebia means worldwide recognition, and thought leadership. This regularly provides us with the opportunity to work on global, innovative projects.

Our mission can be captured in one word: Authority. We want to be recognized as the authority in our field of expertise.

What makes us stand out? It's the little details, like our attitude, dedication to knowledge, and the belief in people's potential - emphasizing every team members development. Obviously, these things are not easy to present on paper – so make sure to visit us to see it with your own eyes!

Now, we've talked a lot about ourselves – but we'd love to hear more about you.

Send us your resume to start the conversation and join the #Xebia.

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. 

Requirements

• 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 – Interview I – Interview II – Decision