Fullstack Engineer

London, England, United Kingdom; New York, New York, United States; San Francisco, California, United States; Seattle, Washington, United States Who We Are Lightning AI is the company behind PyTorch Lightning. Founded in 2019, we build an end-to-end platform for developing, training, and deploying AI systems—designed to take ideas from research to production with less friction. Through our merger with Voltage Park, a neocloud and AI Factory, Lightning AI combines developer-first software with cost-efficient, large-scale compute. Teams get the tools they need for experimentation, training, and production inference, with security, observability, and control built in. We serve solo researchers, startups, and large enterprises. Lightning AI operates globally with offices in New York City, San Francisco, Seattle, and London, and is backed by Coatue, Index Ventures, Bain Capital Ventures, and Firstminute. What We're Looking For We’re looking for a Fullstack Engineer to help develop and scale the Lightning AI platform across the frontend, CLI, APIs, and core backend systems. In this role, you’ll take ownership of key features and drive them end-to-end, working closely with engineering, product, and design to ship high-quality, iterative improvements. This is an opportunity to build systems that support real-world machine learning workloads at scale. This role is based in one of our hubs (NYC, SF, Seattle, or London), with a minimum of 2 in‑office days per week and occasional team and company offsites. We are not able to provide visa sponsorship for this position at this time. What You’ll Do Write readable, testable, and efficient code in React and either Python or Go (Golang). Build deep expertise in our technology stack to deliver new features, improve system stability, and increase overall performance. Partner with engineering and product leaders on developing the Lightning product while using your experience to set the technical direction for large projects. Evaluate, strengthen, and document technical architecture, tools, and processes. Maintain high standards for software quality, implement automation, drive continuous delivery, and reduce time to production while proactively reducing technical debt. Mentor and coach engineers on system design, operating in high uncertainty, and problem-solving to create a supportive, inclusive environment where each engineer can grow. What You’ll Need Proficiency in React and either Go (Golang) or Python, with a preference for Go. Strong understanding of software engineering principles and lifecycle. Hands‑on experience as a Fullstack Engineer in a SaaS technology company. Proven ability to take ownership of key features and drive end‑to‑end development. Communication and collaboration with engineers, product managers, and designers. Ability to operate in high uncertainty and rapidly changing environments. Compensation We are committed to offering competitive compensation that reflects the value each team member brings to our mission. Final offers are based on factors such as experience, skills, geographic location, and role expectations. In addition to base salary, our total rewards package for eligible roles includes a discretionary bonus, a meaningful equity component, and comprehensive benefits. The anticipated annual base salary range for this role is: $120,000 - $250,000 USD Benefits and Perks We offer a comprehensive and competitive benefits package designed to support our employees’ health, well‑being, and long‑term success. Benefits may vary by location, team, and role. Benefits include: Comprehensive medical, dental and vision coverage (U.S.); Private medical and dental insurance (U.K.) Retirement and financial wellness support (U.S.); Pension contribution (U.K.) Generous paid time off, plus holidays Paid parental leave Wellness and work‑from‑home stipends Flexible work environment Equal Employment Opportunity Statement At Lightning AI, we are committed to fostering an inclusive and diverse workplace. We believe that diverse teams drive innovation and create better products. We provide equal employment opportunities to all employees and applicants without regard to race, color, religion, gender, sexual orientation, gender identity, national origin, age, disability, veteran status, or any other protected characteristic. We are dedicated to building a culture where everyone can thrive and contribute to their fullest potential. #J-18808-Ljbffr