Senior JavaScript Engineer

Senior JavaScript Engineer

Ciklum

Remote, Slovakia

About the role:

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

Responsibilities:

• Design and implement rich frontend experiences and scalable backend services that power client's’ wallet infrastructure through the Dynamic platform;
• Own features across the stack: from technical design and architecture through implementation, testing, deployment, and ongoing optimization;
• Build and maintain backend services and APIs supporting authentication, wallets, and payments infrastructure;
• Develop user-facing features and frontend tooling for both end-user and developer-facing applications;
• Collaborate closely with Product, Design, and other engineering teams to deliver robust, high-impact features;
• Contribute to performance, reliability, and scalability improvements across the platform;
• Help uphold engineering best practices through code reviews, testing, documentation, and knowledge sharing.

Requirements:

• 3–5 years of experience building and shipping production-grade, full-stack web applications;
• Experience building backend systems and APIs using Node.js (and frameworks such as Express);
• Comfort working across frontend and backend systems in complex, evolving codebases;
• A strong appreciation for clean, maintainable code and system performance;
• Experience collaborating cross-functionally with product and design partners;
• Curiosity about fintech and Web3, and interest in building infrastructure used at global scale.

Desirable:

• Experience with blockchain technologies (e.g., EVM chains, wallets, on-chain integrations);
• Solidity experience – writing, deploying, testing, or interacting with smart contracts in production environments;
• Experience maintaining, testing, and securing smart contract systems post-deployment;
• Experience with a variety of state management solutions in production React applications;
• Experience with security products or other high-sensitivity domains.