Senior Fullstack Engineer

Nium, Global Leader in Payments Nium, the global leader in real-time, cross-border payments, was founded on the mission to deliver the global payments infrastructure of tomorrow, today. With the onset of the global economy, its payments infrastructure is shaping how banks, fintechs, and businesses everywhere collect, convert, and disburse funds instantly across borders.  Its payout network supports 100 currencies and spans 220+ markets, 100 of which in real-time. Funds can be disbursed to accounts, wallets, and cards and collected locally in 35 markets. Nium's growing card issuance business is already available in 34 countries. Nium holds regulatory licenses and authorizations in more than 40 countries, enabling seamless onboarding, rapid integration, and compliance – independent of geography. The company is co-headquartered in San Francisco and Singapore. 
About the Team      The Growth and Customer Experience team in our San Francisco office builds and owns the GoTo market strategy for various products that take Nium’s market offerings forward using our core banking infrastructure rails.  New initiatives include partner integrations for stablecoins, growth in FX and payroll segment verticals, hosted onboarding and taxes for talent marketplaces and seamless Direct Debit support for PayIns.    The team has rolled out properties like the Nium Client Portal, the central self-service web platform for accessing Nium’s global payments infrastructure and seeks to expand our offerings further for supporting our Hypergrowth phase.     Nium Portal is the single entry point for clients to:     - Create and manage virtual accounts   - Send real-time cross-border payouts   - Issue cards and track balances   - View transactions, FX rates, and reporting dashboards  - Monitor compliance, onboarding, and KYC/KYB workflows      Our users include Fintech developers integrating APIs, as well as operations teams managing high-volume financial workflows. We focus on delivering seamless user experiences and building products that balance self-serve simplicity with deep operational power.     Our goal is to turn complex payment infrastructure into a product experience that is intuitive, scalable, and flexible. As we expand into new markets and product lines, we are investing heavily in frontend engineering, Fullstack capabilities, and product velocity to better serve our customers.     This role will be based out of our San Francisco office and will work closely with our core API teams based in India.    Our Stack    Frontend: React, TypeScript, Next.js, Tailwind CSS, Cypress, D3  Backend: Java, Spring Boot, Nodejs, PostgreSQL, REST APIs  Tooling: Docker, EKS, Grafana, ArgoCD, Flagsmith, LaunchDarkly 

Responsibilities

• Help evolve our fast-prototyping culture to foster innovation and quick market validation 
• Take ownership of the entire application stack and take us through the entire discovery & validation to the customer revenue cycle 
• Be a self-starter and work independently with guidance from Technical mentors and management 
• Strong learning aptitude with demonstrated ability to learn technologies fast and adapt 
• Build user-facing features using React, TypeScript, and Next.js  
• Develop and integrate REST APIs using Java Springboot or Nodejs based technologies 
• Maintain clean, modular, and well-tested code across the stack  
• Contribute to architectural decisions, code reviews, and shared components  
• Optimize for performance, accessibility, and responsiveness  

Requirements

• 4+ years of experience building web applications in production environments 
• Experience with large-scale systems 
• Background in Fintech or global payment systems will be highly preferable 
• Strong knowledge of JavaScript/TypeScript and React/Nextjs 
• Strong focus on Reliability and scalability of applications 
• Exposure to CI/CD and DevOps tools (Docker, feature flags, monitoring) 
• Strong fundamentals in structured programming languages (Java/GoLang/C) 
• Experience integrating with REST APIs and backend systems 
• Solid understanding of frontend fundamentals (HTML/CSS, accessibility, testing)
• Familiarity with backend concepts (Java/Spring Boot, SQL, containers)
• Clear, effective communicati