Founding Software Engineer

About Copperlane (YC W26)

Developer of AI-driven mortgage origination software designed to streamline borrower intake and document processing for lenders. The company's platform offers various features, including an AI assistant that collects and verifies borrower documents, auto-populates application forms, adapts question flows based on loan type, flags inconsistencies before underwriting, and centralizes pipeline management through a unified dashboard, enabling loan officers and operations teams to reduce manual follow-ups, improve application completion rates, and accelerate loan closings with structured, automated, and data-validated workflows.

The opportunity

We're looking for a founding software engineer (member of technical staff) who is obsessed with building agentic AI systems and wants to ship real product from day one. You'll work across the stack but spend most of your time on backend systems, building and orchestrating AI agents that interact with borrowers, loan officers, and third-party platforms in a regulated industry.

This is not a "learn on the job quietly" role. You'll be in the room with customers, see how your code impacts their workflow, and iterate fast. This role is on-site in our San Francisco, CA office.

What you’ll do

• Designing and building agentic AI pipelines: tool use, multi-step orchestration, evaluation, and reliability at scale
• Backend services in Python (FastAPI) on Aurora PostgreSQL and AWS
• Multi-tenant architecture with strong security and compliance boundaries
• Integrations with mortgage industry platforms (LOS systems, voice, messaging)
• Frontend experiences in React, Vite, and TanStack when the product calls for it

What you’ll bring

• Strong fundamentals in backend engineering (Python preferred)
• Hands-on experience building with LLMs: agent loops, tool calling, prompt engineering, evals
• Comfort with PostgreSQL, schema design, and migrations
• Exposure to multi-tenancy patterns, auth, or compliance-aware systems is a plus
• Bonus: sharp design sensibility and strong frontend skills (React, Vite, TanStack). We value engineers who care deeply about craft on both sides of the stack.
• High energy, low ego, genuine curiosity about how things work
• You care about the people using what you build

Experience & eligibility

• Experience: 1+ years
• Visa: US citizen/visa only (as listed on Y Combinator)

Interview process

Expect 1–2 calls with the founders, 1 technical interview, and 1 work trial onsite in San Francisco.