Expert JavaScript Engineer

Job Description Ciklum is looking for an Expert JavaScript Engineer to join our team full-time in Poland. 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. The world of digital assets is accelerating in speed, magnitude, and complexity, opening the door to new ways for leveraging the blockchain. Our Client’s platform and network provide the simplest and most secure way for companies to work with digital assets and it trusted by some of the largest financial institutions, banks, globally-recognized brands, and Web3 companies in the world. The team continues to build and scale the infrastructure and developer tooling that has onboarded 50M+ wallets across crypto and fintech applications. In this context, the team powers the application-layer wallet experience and developer tooling, complementing core custody, security, and transaction infrastructure. The team operates with a strong product mindset and deep focus on security, reliability, scalability, and exceptional developer experience. Engineers build secure-by-default systems and approach their work with a strong customer focus, balancing technical excellence with real-world user needs. You will be joining a passionate group that moves fast, works with the biggest names in payments and fintech, and is defining how the next generation of financial applications are built. Responsibilities Design and implement rich frontend experiences and scalable backend services that power Fireblocks’ wallet infrastructure through the Dynamic platformOwn features across the stack: from technical design and architecture through implementation, testing, deployment, and ongoing optimizationBuild and maintain backend services and APIs supporting authentication, wallets, and payments infrastructureDevelop user-facing features and frontend tooling for both end-user and developer-facing applicationsCollaborate closely with Product, Design, and other engineering teams to deliver robust, high-impact featuresContribute to performance, reliability, and scalability improvements across the platformHelp 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 applicationsExperience building backend systems and APIs using Node.js (and frameworks such as Express)Comfort working across frontend and backend systems in complex, evolving codebasesA strong appreciation for clean, maintainable code and system performanceExperience collaborating cross-functionally with product and design partnersCuriosity 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 environmentsExperience maintaining, testing, and securing smart contract systems post-deploymentExperience with a variety of state management solutions in production React applicationsExperience with security products or other high-sensitivity domains What’s in it for you? Strong community: Work alongside top professionals in a friendly, open-door environmentGrowth focus: Take on large-scale projects with a global impact and expand your expertiseTailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company-paid certificationsEndless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands-on experience with cutting-edge technologiesFlexibility: Enjoy flexibility – full remote working possibilitiesCare: We've got you covered with company-paid premium medical package through LuxmedBenefits: Access the MyBenefit cafeteria platform, allowing you to choose perks that best suit your lifestyle and needs 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. With delivery centers in Wrocław and Gdańsk, our 300+ professionals in Poland drive forward-thinking solutions for global clients. Join a community where collaboration sparks innovation—and your impact reaches millions. 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.