Senior JavaScript Engineer (React.js)
Intellias
- Location
- Poland
- Job Type
- full-time
- Salary
- Unknown
- Posted
- August 22, 2025
Job Description
Make retail great again through the power of technology! Intellias helps retailers provide consistent and customer-centric shopping experiences across all channels with disruptive retail tech solutions. Get on board and make your own contribution to the industry!
What project we have for you
With great experience come great projects. Just imagine: you can develop a product that should completely change the business of one of the world’s largest companies!
Our client is an innovative global company from the Fortune 500. Consumer Goods Producer and Retailer with headquarters in Switzerland that sells its products in 130 countries. Intellias mission is to support its strategy and efforts in the Digital and eCommerce space.
A newly conceptualized Digital Eco System is comprised of a set of capabilities including an online shop & website, linking online & offline, customization & personalization, engagement & membership, digital products & services.
What you will do
- Creating technical vision & documentation
- Participate in architecture and design efforts
- Code review, code optimization
- Technical tasks implementation, design, refactoring
- Collaborate with other engineering teams to resolve dependencies and deliver high-quality software on time, etc.
What you need for this
- University Degree in Computer or Technical Science or strong IT background.
- 8+ years of experience developing React.JS applications.
- 8+ years of HTML front end stack (vanilla-JS, HTML5, CSS) development.
- Experience in modern CSS frameworks (Tailwind/Bootstrap) and CSS3 (e.g., flexbox/grid layouts).
- Experience in module bundlers, and trans pilers.
- Good experience developing Single Page Applications.
- Experience in state-management patterns and libraries (e.g. Redux/Vuex).
- Experience in API integration and API mocking.
- Experience in backend languages is a plus.
- Experience in working with UI design management tools (eg. Figma/Sketch/Invision).
- Autonomy in working with assets and visual (PSD files) is a plus.
- Familiarity with continuous integration and deployment (CI/CD) practices.
- Strong problem-solving skills and attention to detail.
- Solid knowledge of technology used within frontend solutions, specifically NextJS, Adobe stack (Magento & AEM), and Builder.io.
- At least a B2 level of English (Written and spoken).
- On-call support duties
What it’s like to work at Intellias
At Intellias, where technology takes center stage, people always come before processes. By creating a comfortable atmosphere in our team, we empower individuals to unlock their true potential and achieve extraordinary results. That’s why we offer a range of benefits that support your well-being and charge your professional growth.
We are committed to fostering equity, diversity, and inclusion as an equal opportunity employer. All applicants will be considered for employment without discrimination based on race, color, religion, age, gender, nationality, disability, sexual orientation, gender identity or expression, veteran status, or any other characteristic protected by applicable law.
We welcome and celebrate the uniqueness of every individual. Join Intellias for a career where your perspectives and contributions are vital to our shared success.
🎯 Who is this job for?
This Senior JavaScript Engineer (React.js) role at Intellias is tailored for an experienced frontend expert with 8+ years in React, JavaScript, HTML5, and CSS, capable of building scalable SPAs with modern state management (Redux/Vuex). You’ll work on a Fortune 500 global retailer’s digital ecosystem, shaping its architecture, creating technical documentation, reviewing and optimizing code, and collaborating across teams. Experience with Next.js, Tailwind/Bootstrap, Adobe stack (Magento & AEM), Builder.io, and CI/CD practices is highly valued, alongside familiarity with UI tools (Figma, Sketch, InVision). Strong problem-solving, B2+ English proficiency, and occasional on-call support are required. Ideal for a detail-oriented engineer who wants to impact a global-scale retail transformation.
💬 Potential Interview Questions
1. What is your experience with React.js development?
I have over 8 years of experience developing React.js applications, focusing on building scalable, performant, and maintainable single-page applications.
2. How strong is your background in HTML, CSS, and vanilla JavaScript?
I have 8+ years of experience working with the front-end stack, including semantic HTML5, modern CSS (flexbox, grid), and vanilla JavaScript for custom functionality.
3. What CSS frameworks and tools have you worked with?
I have worked extensively with TailwindCSS and Bootstrap, as well as modern CSS3 features, ensuring responsive and visually consistent designs.
4. What is your experience with state management libraries like Redux?
I have implemented Redux in multiple large-scale applications, managing complex state across components efficiently and integrating middleware for side effects.
5. How do you approach building single-page applications?
I design SPAs with modular architecture, reusable components, optimized routing, and API-driven data handling to ensure scalability and performance.
6. What is your experience with Next.js or similar frameworks?
I have experience using Next.js for server-side rendering, static site generation, and performance optimization in enterprise-level projects.
7. Have you integrated APIs in your projects?
Yes, I have integrated REST and GraphQL APIs, using best practices for error handling, caching, and API mocking for development and testing.
8. What UI design tools have you worked with?
I am comfortable working with Figma, Sketch, and InVision, collaborating closely with designers and independently handling visual assets when needed.
9. What is your experience with CI/CD?
I have used GitHub Actions and Jenkins to automate testing and deployment pipelines, ensuring smooth integration and continuous delivery.
10. Are you comfortable with on-call support duties?
Yes, I have experience providing on-call support, monitoring applications, troubleshooting production issues, and ensuring high availability.
11. What backend experience do you have?
I have basic experience with backend languages like Node.js, which helps me collaborate better with backend teams and contribute when needed.
12. How do you ensure code quality and scalability in frontend projects?
I follow best practices in clean code, conduct code reviews, optimize performance, implement testing with Jest/React Testing Library, and ensure accessibility compliance.
📋 Job Summary
Intellias is a global technology partner helping Fortune 500 retailers and consumer goods companies transform their digital and eCommerce strategies with innovative solutions. For this project, engineers will contribute to building a newly designed Digital Ecosystem that powers online shops, personalization, customer engagement, and seamless online-offline integration, shaping the future of retail for a Swiss-based multinational operating in 130 countries.