Sr. Full-Stack Engineer (Frontend Heavy)

Senior Full-Stack Engineer (Frontend-Heavy) Location: Irvine, CA 92618 Work Style: Hybrid (3 days/week in office) Work Hours: 9:00 AM – 6:00 PM Salary Range: $110,000 – $120,000 base Experience Level: 5–10 years Work Authorization Requirement: Due to company policy, we are unable to provide visa sponsorship now or in the future. Candidates must be legally authorized to work in the United States on a permanent basis. Applicants requiring visa sponsorship cannot be considered. About the Company A growing software company based in Irvine, California is seeking a Senior Full-Stack Engineer to help expand and evolve a modern B2B customer support and ticketing platform primarily serving Japanese business customers. This is a unique opportunity to join a small, collaborative product team where your work directly impacts customers and product direction. The team works closely with global counterparts and values ownership, technical excellence, and thoughtful product development. The Role We are looking for a Senior Full-Stack Engineer with strong frontend expertise to help build and scale a modern SaaS platform. This is a full-stack role with a strong emphasis on React + TypeScript frontend development, while also contributing to backend APIs and platform architecture as needed. You will collaborate closely with engineering, product, and leadership teams to deliver scalable, high-quality user experiences and technical solutions. What You’ll Do Modernize and scale a React + TypeScript application while improving architecture and code quality Build and expand a reusable UI component library using MUI Design and improve frontend state management and data-fetching architecture Drive frontend performance improvements including code splitting, lazy loading, caching, and optimization Develop responsive and polished user experiences across devices and screen sizes Deliver full-stack features from backend APIs through frontend implementation Improve and maintain backend services including REST APIs, GraphQL APIs, background workers, and scheduled jobs Establish engineering best practices, code review standards, and scalable development patterns Collaborate closely with cross-functional and international teams Technology Stack Frontend React, TypeScript, MUI, TipTap (rich-text editing) Backend Node.js, Bun, REST API, GraphQL Infrastructure & Data PostgreSQL, Redis, RabbitMQ, Meilisearch, Qdrant, Docker, Kubernetes Additional AI-powered platform features Required Qualifications 7+ years of software engineering experience Strong recent experience with React and TypeScript- You have led and taken ownership of complex React applications, not just contributed as part of a larger team. Deep understanding of modern React concepts including: Hooks, Suspense, Code splitting, Lazy loading, Performance optimization Strong experience with frontend state management and caching strategies Experience modernizing and scaling production applications Solid understanding of responsive UI development and modern CSS Experience building accessible and polished user interfaces Full-stack development experience including backend development with Node.js or similar technologies Experience working with relational databases such as PostgreSQL Strong communication and collaboration skills Ability to work independently within a small agile team Business-level English communication skills Preferred Qualifications Experience with GraphQL (Apollo, urql, etc.) or tRPC Experience with Bun, Hono, or modern JavaScript runtimes/frameworks Familiarity with RabbitMQ, Meilisearch, or vector databases Experience with Docker and Kubernetes Experience building or maintaining design systems/component libraries Familiarity with TipTap or ProseMirror React Native or mobile development experience Experience working on SaaS, B2B, or ticketing/support platforms Japanese language skills are a plus Work Environment Hybrid schedule: 3 days/week onsite in Irvine, CA Collaborative and highly technical small-team environment Opportunity for meaningful ownership and direct product impact Long-term growth opportunity within an expanding product organization