Senior Founding Engineer

Job Description Job Description About the Role We're hiring a Senior Founding Engineer to help architect and scale the systems behind one of the fastest-growing platforms in conversational AI infrastructure. This is a deeply technical, architecture-heavy full stack engineering role focused on building systems that operate reliably at massive scale. The platform already handles millions of real-time conversations every month, and the engineering team is looking for someone who has built and optimized production systems operating at that level of complexity. You'll work directly with the founding team in a highly collaborative onsite environment, owning problems across the stack — from backend infrastructure and database optimization to frontend performance and real-time communication systems. This role is ideal for engineers who thrive in fast-moving startup environments, enjoy solving large-scale systems challenges, and bring exceptional craftsmanship and intensity to both work and personal pursuits. About the Company The company is building the world's first quality assurance and observability platform for conversational AI agents. Founded by former AI engineers from Microsoft and AWS, the platform enables organizations to simulate, evaluate, monitor, and improve AI voice and text agents before they interact with real customers. Backed by Y Combinator, Floodgate, and PeakXV, the company has experienced explosive growth since launch: Surpassed $100K ARR within the first month during YC Doubled growth every three months since inception Surpassed $1M in revenue Currently processing millions of calls monthly Customers include major organizations such as Google, DoorDash, Sallie Mae, and other rapidly growing enterprise customers. What You'll DoArchitecture & Systems Engineering Architect and develop systems for simulating, analyzing, and evaluating conversational AI agents Build scalable infrastructure capable of handling millions of real-time conversations Design resilient distributed systems using AWS services including Lambda, EC2, WebSockets, and SIP Optimize performance across the stack including database queries, APIs, and frontend rendering performance Reduce bottlenecks and improve platform responsiveness at scale AI Infrastructure & Product Development Develop pipelines and algorithms that surface insights, detect failures, and evaluate AI behavior Build systems that improve AI reliability, safety, and observability Develop full stack product experiences spanning backend services and frontend applications Work directly with customers to deploy and improve products in real-world environments Engineering Leadership Establish strong engineering practices across architecture, system design, and code review Contribute to technical direction and long-term scalability planning Collaborate closely with founders in a highly iterative product environment Required Qualifications 6+ years of full stack software engineering experience Deep expertise across both frontend and backend engineering Strong proficiency in: TypeScript Python SQL AWS infrastructure Strong systems architecture and distributed systems thinking Experience building and optimizing production systems operating at significant scale Experience handling high-throughput systems, large datasets, or millions of requests Strong communication skills and collaborative working style Comfortable operating in fast-paced startup environments Demonstrated obsession/mastery outside of work requiring long-term deliberate practice and discipline Preferred Visa Status US Citizenship or Permanent Residency strongly preferred H-1B transfers considered Tech StackFrontend React Next.js Tailwind CSS TypeScript Backend & Infrastructure Python FastAPI Supabase Redis AWS (Lambda, EC2, WebSockets, SIP) Voice AI & Real-Time Systems LiveKit Deepgram Cartesia ElevenLabs Gemini WebSockets DevOps & Tooling CI/CD pipelines Preferred Qualifications Previous experience as a founding engineer at a YC-backed startup Experience building voice AI or conversational AI systems Strong frontend product design and UI craftsmanship Experience as a technical founder or startup operator Background at high-performance AI or infrastructure companies Compensation & BenefitsCompensation Base Salary: $200,000 – $250,000 USD Benefits & Perks Health insurance Gym membership reimbursement $500 desk and workspace stipend Work Environment Location: San Francisco, California Fully onsite with the founding team Office expansion underway as the company scales rapidly High-intensity, high-ownership startup culture Why This Role Stands OutMassive Scale Challenges The platform is already operating at production scale with millions of real-time conversations each month, creating meaningful distributed systems and performance engineering challenges. Foundational Ownership You'll directly influence architecture, infrastructure, engineering standards, and product direction alongside the founding team. Elite Technical Environment Work with experienced AI and infrastructure leaders from Microsoft, AWS, and top-tier startup ecosystems. Real Product & Customer Impact Your systems directly shape the reliability and performance of AI agents deployed into real-world customer environments. High-Performance Culture The company values craftsmanship, intensity, curiosity, and people who pursue mastery both inside and outside of engineering.