Expert JavaScript Engineer

Ciklum is looking for an Expert JavaScript Engineer to join our team full-time in Ukraine.

We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live.

About the role:

As an Expert JavaScript Engineer , become a part of a cross-functional development team engineering experiences of tomorrow.

Ciklum’s client is a global payments technology company providing payment processing, acquiring, and financial technology solutions to businesses worldwide.

Responsibilities:

• Lead the architectural transition and rewrite of legacy ASP.NET web applications into modern, scalable React.js and TypeScript frontends
• Analyze existing system behaviors to ensure 100% functional parity and continuous user experience during the modernization process
• Build modular, maintainable, and scalable component libraries using React.js, TypeScript, and state management workflows (e.g., Redux, Flux)
• Design and implement responsive, secure, and intuitive user interfaces tailored for high-stakes transactional operations
• Leverage strong proficiency in core JavaScript, DOM manipulation, state management, and modern CSS to deliver fast and reliable UI components
• Collaborate with backend teams to design, integrate, and consume RESTful APIs and backend microservices securely and efficiently.
• Implement automated frontend testing suites to ensure cross-browser compatibility, security, and UI stability
• Utilize Git (or legacy VCS like SVN/Mercurial) and participate in CI/CD release pipelines within Azure DevOps environments

Requirements:

• Strong proficiency in React.js, TypeScript, JavaScript (including DOM manipulation and object model), HTML5, and CSS3
• Thorough understanding of modern frontend architecture, React core principles, and state management workflows (e.g., Redux, Flux)
• Proven experience migrating legacy web applications (preferably ASP.NET) to React while preserving existing business logic and system functionality
• Experience building secure, responsive, and intuitive interfaces for complex, high-stakes transactional workflows
• Strong understanding of RESTful API integration, data flow handling, and microservices-based application design
• Proficiency with Git and code versioning practices (familiarity with SVN or Mercurial is a plus)
• Experience with automated frontend testing frameworks and continuous integration tools like Azure DevOps or similar
• Upper-Intermediate level of English or higher

Desirable: 

• Deep understanding of payment gateway architecture, transaction lifecycles, and payment domain security
• .NET experience

What’s in it for you?

• Strong community: Work alongside top professionals in a friendly, open-door environment
• Growth focus: Take on large-scale projects with a global impact and expand your expertise
• Tailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company-paid certifications
• Endless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands-on experience with cutting-edge technologies
• Flexibility: Enjoy radical flexibility – work remotely or from an office, your choice
• Care: We’ve got you covered with company-paid medical insurance, mental health support, and financial & legal consultations

About us:

At Ciklum, we are always exploring innovations, empowering each other to achieve more, and engineering solutions that matter. With us, you’ll work with cutting-edge technologies, contribute to impactful projects, and be part of a One Team culture that values collaboration and progress.

As one of Ukraine’s largest IT companies and a top employer recognized by Forbes, we’ve spent over 20 years delivering meaningful tech solutions. We proudly support diverse talent and military veterans, recognizing their unique skills and perspectives they bring to shaping the future.

Explore, empower, engineer with Ciklum!

Interested already? We would love to get to know you! Submit your application. We can’t wait to see you at Ciklum.

#LI-NV1