Fullstack Software Engineer

About the Role We are on a mission to revolutionize B2B payments. We’re a well-funded, early-stage startup operating in stealth mode, building cutting-edge solutions that will transform the way businesses move money. As we grow, we are looking for a Fullstack Software Engineer to join our Platform team and help build the core infrastructure that powers our payment solutions. You’ll work on challenging technical problems while contributing to the foundation of our technology stack. As a Fullstack Software Engineer, you will be pivotal in designing, building, and maintaining web applications and the APIs that power them. You’ll focus on crafting intuitive, secure, and responsive UIs while architecting backend systems that support large-scale financial transactions with real-time processing capabilities. In an agile environment, you’ll report to the Engineering Manager and collaborate with a cross-functional team of engineers, designers, and product managers. This role is ideal for someone who enjoys working across the stack, thrives in early-stage environments, and is passionate about building secure, compliant financial technology. Key Responsibilities Frontend Development: Build and maintain modern, responsive, and secure web applications using ReactJS with TypeScript, focusing on performance and accessibility. UI Frameworks: Leverage React-based libraries to create enterprise-grade UI components that meet financial industry standards. Backend Development: Design, build, and maintain RESTful APIs and GraphQL endpoints. Database & Data Management: Design efficient data models and work with SQL and NoSQL databases to securely handle transactional and analytical workloads. Real-time Systems: Implement websockets, message queues, and event-driven architectures to support real-time payment processing and notifications. Testing & Quality: Write comprehensive tests using Jest, Cypress, or Playwright to ensure system stability, and participate in code reviews to maintain high code quality standards. Web Security: In compliance with financial regulations, apply advanced security practices, including CSP implementation, secure coding principles, data encryption, and vulnerability assessment. Performance Optimization: Implement data compression, caching strategies, CDN optimization, and monitoring to enhance speed, scalability, and system observability. Collaboration: Work closely with Product, Design, and Platform teams in an agile environment to deliver features that delight customers while meeting compliance and reliability standards. Mentorship: Participate in code reviews and knowledge sharing, and mentor junior developers as the team grows. Required Qualifications Experience: 5+ years of software engineering experience, including significant fullstack development focusing on frontend applications and backend API development. Strong proficiency in ReactJS and modern JavaScript/TypeScript Solid experience with backend frameworks (Node.js, Java/Spring, or similar) Hands-on experience with both SQL and NoSQL databases Understanding of data modeling and database optimization Testing: Hands-on experience with Jest, Cypress, Playwright, or other modern testing frameworks, focusing on test-driven development. System Design: Experience designing scalable web applications, microservices architecture, and API integration patterns. Agile Development: Experience with Scrum/Agile methodologies, sprint planning, and collaborative development practices. Problem-Solving: Ability to debug and optimize for performance, security, and reliability. Communication: Excellent communication skills in a collaborative, fast-paced environment. Preferred Qualifications Fintech Experience: Background in fintech, banking APIs, payment processing, or commercial payments systems. Real-time Systems: Experience with websockets and real-time data processing. Enterprise UI/UX: Exposure to enterprise-grade UI/UX standards in regulated industries. Why Join? Cutting-Edge Work: Build highly scalable applications that power transformative B2B payment solutions using the latest technologies. End-to-End Impact: Own critical features across the stack, directly influencing product direction and technical architecture. Security & Scale: Tackle complex engineering challenges in financial compliance, web security, and high-scale distributed systems. Early-Stage Growth: Shape our technology foundation and engineering culture while growing your career in a well-funded startup. Learning & Development: Gain deep expertise in fintech, security-first development, distributed systems, and regulatory compliance. Team Culture: Work with a collaborative, diverse team that values technical excellence, continuous learning, and work-life balance. We’re building transformative technology in payments and looking for curious, driven people to join us. Whether or not you meet every qualification, what matters most is your initiative, willingness to grow, and passion for building secure, performant, and user-friendly web applications. We embrace AI as a powerful tool for innovation and welcome team members eager to leverage it in their work. As an equal opportunity employer, we’re committed to diversity, inclusion, and creating an environment where everyone can thrive. Seniority level Mid-Senior level Employment type Full-time Job function Engineering and Information Technology Industries Advertising Services Referrals increase your chances of interviewing at Confidential by 2x Get notified about new Software Engineer jobs in San Diego, CA . We’re unlocking community knowledge in a new way. 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