Staff/Principal Frontend Software Engineer

ABOUT THE COMPANY America is under sustained cyber attack. Our adversaries infiltrate our networks, steal our IP, and degrade the digital infrastructure that modern life runs on. They’ve learned—correctly—that those attacks rarely produce consequences. Twenty was founded to change that, by making our adversaries think twice before they attack us. Our vision is American and allied primacy in cyberspace—a future where they cannot contest us, deterrence is assured, and the free world remains secure. Founded in 2024, Twenty Technologies (www.twenty.io http://www.twenty.io) industrializes offensive cyber operations for the U.S. and its allies. Headquartered in Arlington, Virginia, Twenty has raised $168M from Khosla Ventures, Accel, Caffeinated Capital, Friends & Family Capital, Point72 Ventures, General Catalyst, and In-Q-Tel.     Mission | On Site | Full Time | U.S. Citizenship Required / No Active Clearance Required     ROLE SUMMARY You'll own the frontend architecture for mission-critical operator experiences—building high-performance interfaces that visualize complex cyber operation data in real time. You'll lead technical direction for UI systems, set the bar for engineering quality, and mentor engineers to move faster with confidence. You'll partner closely with backend, product, design, and operational stakeholders to ship capabilities that must work reliably in both cloud and on-premises environments. You'll be embedded in a cross-functional team building capabilities that go directly into operational use — small team, tight feedback loops, real consequences.   WHAT YOU'LL DO - Architect and build sophisticated React/TypeScript applications that operate smoothly at scale. - Design real-time UI experiences for complex cyber operation data, optimizing for speed and clarity. - Lead frontend technical architecture and design decisions. - Build and evolve interactive visualization systems (e.g., graphs, timelines, streaming views). - Establish reusable frontend architecture patterns and component libraries for consistency and velocity. - Raise engineering excellence via code review, standards, testing strategy, and performance practices. - Mentor junior engineers through pairing, feedback, technical coaching, and knowledge transfer. - Coordinate execution across design, product, backend, and operations to deliver end-to-end features. - Troubleshoot production issues, lead frontend performance investigations, and improve reliability over time. WHO YOU ARE - You care about building software that has real-world impact in high-stakes environments. - You lead with high standards and high support—clear feedback, strong mentorship, calm execution. - You think in systems: performance, reliability, accessibility, and maintainability are first-class concerns. - You make good tradeoffs under constraints and can explain them crisply to technical and non-technical partners. - You enjoy turning complex data into intuitive workflows that help users make decisions quickly. - You’re comfortable owning ambiguous problems end-to-end and driving them to measurable outcomes. - You default to secure engineering practices and treat trust, safety, and correctness as non-negotiable.   MUST HAVE - You have 8+ years of professional frontend software development experience. - You have deep expertise building production React.js applications with TypeScript. - You have strong command of modern web fundamentals (JavaScript/TypeScript, HTML, CSS). - You have led frontend technical initiatives and mentored engineers through delivery and growth. - You have experience building for performance at scale (profiling, optimization, rendering strategies). - You have experience with automated testing practices and frameworks (e.g., Vitest, React Testing Library, Playwright or Cypress for E2E). - You have hands-on experience with state management patterns and libraries (e.g., Redux, Zustand, or React Query). - You have strong collaboration skills with product and design to deliver excellent UX. - You have strong command of Git in a professional engineering environment, including branch workflows, code review practices, and CI integration. - You have a Bachelor’s degree in CS/Engineering (or equivalent practical experience). NICE TO HAVE - You have experience with complex data visualization (e.g., D3.js, Chart.js, or similar). - You have worked with graph databases and understand graph query patterns (e.g., Neo4j). - You have experience with real-time streaming data and production visualization of live systems. - You have experience in defense, security, or other mission-critical domains. - You have built UI experiences that surface AI/ML outputs in operational workflows. - You have experience with component library or design system development (e.g., Storybook). Benefits What's on the table: - Health. Medical, dental, and vision plan options. Life / AD&D, disability coverage options. - Family. Paid parental leave for eligible full-time employees. 12 weeks for birthing parents, 4 for non-birthing parents, 6 weeks for adoptive, foster, or intended parents through surrogacy. - Vacation. Paid holidays and flexible PTO. Take what you need. - Retirement. 401(k) with pre-tax and Roth options. HSA/FSA options, dependent care FSA. Benefits vary by location, role, and eligibility. Full plan details provided during the interview and offer process. If this role sounds like you, apply and share with us your interest Due to U.S. government contract and security requirements, this role is limited to U.S. citizens. Some positions may also require eligibility to obtain and maintain a U.S. Government security clearance. Any active clearance requirement will be listed in the role description. Twenty is an equal opportunity employer. We consider all qualified applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, veteran status, disability, or any other protected status, consistent with applicable law. If you need a reasonable accommodation during the hiring process, let us know and we will work with you.