Founding Product Engineer

About the Role Join a small B2B SaaS team building AI-driven pricing and monetization software. In this hands-on, senior role, you will own product modules end to end, work directly with customers and leadership, and help shape the architecture behind reliable financial workflows and agent-driven experiences. What You'll Do Scope customer problems, design versioned APIs, build user interfaces, and ship complete product modules. Design and evolve architecture for AI-driven workflows across web, conversational interfaces, command-line tools, and integrations. Make product capabilities accessible to LLM agents through agent tooling and conversational interfaces. Move pricing and business logic into backend services to ensure financial accuracy. Extend typed pricing and product data models, and lead architectural discussions focused on security and extensibility. Establish testing, observability, deployment, and performance practices for AI features. Mentor teammates, contribute to product direction, and investigate production issues with a focus on root causes. What We're Looking For At least 8 years of software engineering experience, including staff-level ownership of product areas at startups. Strong backend experience with Python, FastAPI, and MongoDB or a comparable stack, plus React and TypeScript skills to build polished interfaces independently. Experience taking customer problems from discovery through delivery, including server-side business logic, versioned APIs, data models, and production operations. Background with AI-assisted product features or agent-driven workflows; experience with MCP-like tooling is a plus. Familiarity with B2B SaaS pricing, packaging, quoting, billing, or CPQ, and a high standard for financial correctness. Must be authorized to work in the United States without visa sponsorship. Compensation & Benefits Base salary: $200,000 to $250,000 annually. Visa sponsorship is not available. Location On-site in San Francisco, California. Candidates must be based in or willing to relocate to San Francisco.