Founding Product Engineer

About the Role This is a founding-team engineering role at an early-stage AI-driven pricing and monetization platform for B2B SaaS companies. You'll own entire product modules end-to-end — from scoping with customers through architecture, implementation, and iteration — working directly alongside product and leadership on a small, high-trust team where your decisions shape the product and engineering culture. What You'll Do Own whole product modules end-to-end: scope with customers, design versioned APIs, build the UI, ship, and iterate. Design and evolve architecture for agentic AI systems across Slack bots, terminal UIs, web interfaces, and vendor integrations. Ensure features are drivable by LLM agents via MCP/FastMCP servers and conversational interfaces. Move pricing and business logic off the client into backend services to preserve financial fidelity. Extend and maintain a typed pricing ontology (e.g., Pydantic models for SKU, Proposition, Persona, Pricing, and more). Lead architectural reviews and technical discussions to keep systems robust, extensible, and secure. Establish testing, observability, deployment, and performance monitoring practices for AI-driven features. Mentor peers, influence product strategy, and set engineering best practices. Treat money-handling code as load-bearing infrastructure and prioritize root-cause analysis for production issues. What We're Looking For 8+ years of software engineering experience with proven ownership of full product areas at startup or staff-level scope. Deep backend expertise with FastAPI, Python, and MongoDB (or a comparable stack) in production environments. Credible full-stack range: ability to design versioned REST/GraphQL APIs and ship polished React + TypeScript UIs independently. Track record of taking ambiguous customer problems to shipped features without a dedicated PM. Familiarity with B2B monetization concepts: pricing models, packaging, quoting, billing, or CPQ. Experience building or integrating AI-assisted features and agent-driven workflows (LLM interfaces, MCP-like endpoints). High standards for correctness, especially in financial and pricing logic. Nice to have: Built MCP servers or tooling for LLM agents; experience with billing, CPQ, or metering systems; prior early employee or co-founder at a 0-to-1 B2B product; familiarity with SOC 2/GDPR constraints. Must be authorized to work in the United States; no visa sponsorship available . Compensation & Benefits Base salary: $200,000 – $250,000 USD annually . Equity participation expected at founding-team level. Location On-site in San Francisco, CA, United States . Remote candidates will not be considered for this role.