Senior Full Stack Engineer – Payments & Developer Platforms (TypeScript)

Job Title: Senior Full Stack Engineer – Payments & Developer Platforms (TypeScript)Location: San Francisco, CA (Downtown – Hybrid: 4 days in-office, 1 day WFH)Industry: High-Growth Tech / Developer InfrastructureCompensation: $175,000 - $250,000 Base Salary + Competitive EquityCompany Size: Small, early-stage elite startup (Estimated 10–50 employees)Headquarters: San Francisco, CaliforniaWhat They Do:Our client builds the developer infrastructure and environment "plumbing" required for autonomous AI agents. Specifically, they provide secure, stateful, and sandboxed cloud environments where AI software agents can safely execute code, interact with operating systems, use developer tools, and perform complex browser actions. They essentially build the sandbox that prevents an AI agent from breaking the system it's working on.About the Opportunity: Our client is scaling their engineering team and looking for three Senior Full Stack Engineers who thrive on building high-density systems, developer-facing APIs, and secure, high-scale transactional pipelines.This is a role for a true "builder" who wants to own systems end-to-end, work within a tight-knit engineering culture, and deploy production-grade software directly to production.Key Responsibilities:Developer Products & APIs: Design, build, and optimize developer-facing products, robust internal tools, and highly scalable public APIs.Payments & Integrations: Architect, scale, and maintain secure, core payment workflows and complex third-party system integrations (e.g., Stripe).Infrastructure & Security: Own containerization and orchestration workflows (Docker, Kubernetes) and maintain state-of-the-art authentication and identity management systems (Keycloak/OAuth concepts).System Adaptation: Act as a core individual contributor capable of reasoning through complex legacy architectures and rapidly adapting systems to support business growth.What You Bring (Required):Experience Baseline: 4 to 7 years of full-stack engineering experience. Crucially, your background must reflect time spent scaling products inside a fast-paced Series B-D startup or a high-growth tech environment (e.g., Stripe, Retool, Square).The Stack: Advanced proficiency with TypeScript, combined with solid, hands-on experience using Docker and Kubernetes in production environments.Domain Depth: Proven track record of handling payment integrations and a rock-solid grasp of core authentication systems and concepts.Education: Bachelor’s degree in Computer Science, Electrical Engineering, or a highly related technical field from a top 50 university.Logistics: Ability to work on-site 4 days a week in our Downtown San Francisco office. Must be authorized to work in the U.S. without requiring new visa sponsorship (TN/Canadian visa transfers are fully acceptable).Traits We Avoid for This Role:Career paths spent exclusively at large "mega-tech" (FAANG) companies or entirely within non-tech traditional corporate legacy industries (e.g., insurance, traditional healthcare).A history of multiple short stints (<1.5 years) early in your career.