Senior Frontend Software Developer - React (m/f/d)

Our brand Deutsche Telekom IT Solutions Slovakia entered the life of Košice region in 2006 under the name of T-Systems Slovakia and ever since has been inextricably linked with the region when became one of the founding members of Košice IT Valley. We have managed to grow from scratch to the second largest employer in the eastern part of the country with more than 3900 employees. Our goal is to proactively find new ways to improve and continuously transform into the type of company providing innovative information and communication technology services. We are looking for a Senior Frontend Developer/Engineer to join the team behind Charisma and take technical ownership of modern user interfaces for a solution supporting complex operational and rollout processes. You will lead the development and continuous improvement of React applications and Bryntum-based user interfaces, with a strong focus on architecture, scalability, performance, maintainability, accessibility, and quality. Beyond delivering new functionality, you will guide technical decisions, improve existing production applications, strengthen frontend standards, and help expand test automation across the project. You will work closely with frontend and backend engineers, quality engineers, business experts, customers, and stakeholders in an agile delivery environment, translating complex business needs into sustainable user-facing solutions and supporting the Frontend Software Developer working on the same project. WHAT WILL YOU DO? Lead the design, development, and continuous improvement of modern frontend applications using React and TypeScript Define and apply frontend architecture standards using JavaScript ES6+, HTML5, CSS3, and Material UI Design, build, and optimize advanced Bryntum-based interfaces and components Translate complex customer and stakeholder requirements into scalable, intuitive, and maintainable frontend solutions Own frontend integration concepts with backend services using REST APIs and WebSockets Provide advanced guidance on React Hooks, React Router, Redux, and Redux Toolkit Drive component-based architecture, state management, clean code principles, design patterns, and frontend best practices Improve application responsiveness, accessibility, technical consistency, and overall frontend performance Shape and contribute to Micro Frontend architectures together with the development team Lead the design and maintenance of automated frontend and UI tests using React Testing Library, Cypress, and Playwright Promote Test-Driven Development practices and pragmatic quality standards where appropriate Work with Git, CI/CD pipelines, and Docker and support improvements to the development lifecycle Lead collaborative code reviews, mentor less experienced developers, and support the Frontend Software Developer working on the same project Coach and mentor through, technical guidance, code reviews, and knowledge sharing Support the professional growth of frontend team members by sharing best practices, explaining architectural decisions, and helping establish consistent engineering standards Work in an agile environment using Scrum, Kanban, or LeSS , actively contributing to planning, refinement, and delivery discussions Take a senior role in stabilizing the production solution, resolving complex issues, and supporting further rollout activities with customers and stakeholders YOU WILL SUCCEED IF YOU: have: Extensive hands-on experience with React in complex production applications Advanced knowledge of JavaScript ES6+, TypeScript, HTML5, and CSS3 Strong experience building scalable user interfaces with Material UI Strong experience integrating frontend applications with REST APIs and aligning API contracts with backend teams Advanced experience with WebSocket management and real-time user interfaces Deep practical experience with React Hooks, React Router, Redux, and Redux Toolkit Strong experience working with and extending Bryntum Components Strong understanding of responsive design and accessibility, including WCAG Advanced understanding of component-based architecture, state management, clean code, and design patterns Proven experience with frontend performance optimization in production environments Practical understanding of Micro Frontend architectures and their operational trade-offs Strong experience with frontend testing strategy and test automation using technologies such as React Testing Library, Cypress, and Playwright Practical understanding of Test-Driven Development and quality-driven engineering practices Strong practical experience with Git, CI/CD pipelines, and Docker Experience mentoring developers, reviewing technical designs, and improving team engineering practices Proven ability to mentor frontend developers, provide constructive technical feedback, and raise the technical maturity of the team Experience communicating with customers, stakeholders, business experts, and cross-functional teams Experience working in agile development environments and with Jira , including refinement, planning, and delivery coordination And speak English (min. level B2). Nice to Have: Experience leading or shaping Single-SPA Micro Frontend solutions Experience with Next.js Experience with Vite and modern frontend build optimization Experience with GraphQL Experience with Web Components Experience acting as a technical counterpart for customer-facing discussions, demos, or rollout support Experience using AI-assisted development tools such as GitHub Copilot or Microsoft 365 Copilot WHY SHOULD YOU CHOOSE US? We believe in balance between work and personal life. An attractive and extensive work-life balance portfolio guarantees lasting motivation for employees and thus a better quality of life, promotes physical and mental well-being and contributes to a positive work environment. All this with the aim of providing more freedom in reconciling work, career growth, private life and individual lifestyle. Therefore we offer to our employees over 25 different benefits to improve their personal and professional life in these areas: Financial benefits Benefits with focus on learning and development Benefits with focus on health and sport Benefits with focus on family and work – life balance Other benefits For more information about our benefits click to Benefits Salary Final salary is negotiable. We are offering base salary depending on seniority level and previous experience of candidate. In addition to base salary we provide variable part and other financial benefits. Base salary will not be lower than 3100€ /brutto. Additional information * Please be informed that our remote working possibility is only available within Slovakia due to European taxation regulation.