Founding Full-Stack Engineer

Job Description

Job Description

About the Company

A pre-seed FinTech startup building the financial infrastructure for the agentic web — turning intent into action by giving AI agents a dependable way to reach businesses, prove who they are acting on behalf of, and pay for the transactions they conduct. Founded in 2025 by operators with deep payments-network backgrounds, the team is focused on end-to-end agentic purchasing: letting an AI agent autonomously complete real transactions across commerce protocols and payment providers.

Founded 2025 · Team of 3 · Industry: FinTech

The Role

This is the company's second founding engineer hire, building the platform end-to-end with particular focus on two core products: programmable, scope-limited payment credentials tied to a user's existing card, and an agentic checkout that lets agents complete real transactions across commerce surfaces. Because the products move money and assert identity on behalf of real people, correctness and reliability matter throughout the stack, not just at the infrastructure layer.

What you'll be doing

• Design and build features end-to-end, from merchant/developer interfaces through to services, APIs, and data models.
• Turn programmable payment credentials and agentic checkout capabilities into reliable, well-designed product surfaces.
• Design and maintain the APIs that merchants, developers, and partners build on — keeping the external surface simple while absorbing the underlying complexity.
• Build software around LLMs and agents, including the tooling and guardrails that keep them dependable.
• Share responsibility for testing, monitoring, and operational health, holding a high bar for correctness as the product grows.
• Help shape the engineering culture as the 2nd engineering hire.

Tech stack: JavaScript-based, with Python for MCP, all on AWS

Requirements

• 0-3 years engineering
• Agent harness / agent building experience
• JavaScript + Python + AWS
• High agency, opinionated, generative thinker
• SF North Beach, 5 days in-person + occasional weekends
• Scrappy AI-native generalist (NOT 10-year infra)

Green Flags

• Strong agent harness or agent building portfolio. Direct match for the company's product.
• Hackathon-heavy background paired with shipping discipline. Demonstrates developer experience and agent integration intuition.
• Scrappy, AI-native generalist with side projects and high agency.
• Fintech adjacency (Stripe, Plaid, Visa, crypto startups, payments tools)
• Comfortable being raw and malleable. Wants to take on more responsibility than they've had at this point in their career.

Red Flags

• 10-year infra engineer wanting Staff or Principal title.
• Pure rule-follower who needs a spec to operate.
• Big-team-only background with no scrappy chapter. Case-by-case but generally not a fit.
• Cannot work SF in-person 5 days a week + occasional weekends

Why Join

• Founding seat as the 2nd engineering hire, with direct latitude to shape both the product and the engineering culture.
• A genuinely novel space — building end-to-end agentic purchasing with an approach nobody else is taking.
• Full-stack ownership from day one across the company's two core products.

Details

• Location: San Francisco, CA (North Beach)
• Work policy: On-site, 5 days/week + occasional weekends, startup hours
• Compensation: $150,000–$200,000 + 0–2% equity
• Visa sponsorship: O-1 available; H-1B transfer + OPT supported
• Employment type: Full-time