Founding Full Stack Engineer

Founding Full Stack Engineer

( Founding Role, Hybrid )

Have any questions? Reach out at hello@lendkoi.com

About the role

We're looking for a Founding Full Stack Engineer to build our lending platform end-to-end — from the borrower-facing web app through the Django API and the fintech integrations that move money and make loans work. This is a genuinely full-stack codebase, not frontend-with-a-BFF: most features touch both the app and the backend. You'll own problems from ticket to production, raise the engineering bar as the team grows, and work closely with experienced leaders, a cross-functional team, and our vendor partners.

The compensation for this role is pay + equity. Flexible New York City hybrid. Full time.

The stack you'll work in

Frontend: Next.js, React, TypeScript, TanStack React Query, Zustand, React Hook Form + Zod, and a shared component library built on Radix UI + MUI.

Backend: Django + Django REST Framework, Python, PostgreSQL, Celery, Redis.

Schema-first API: OpenAPI schema that generates a fully typed TypeScript client - types flow from Django serializers to React components, so schema drift is caught at compile time, not in production.

Infrastructure: AWS (Elastic Beanstalk and core services), GitHub Actions CI/CD

Fintech Integrations.

Preferred

Experience designing and supporting the AI/data-science model lifecycle in fintech - from architecture and prototyping through to production-grade code and application integration, alongside the engineering team.

Credit risk, underwriting, or cash-flow modeling experience.

Familiarity with fair-lending, model-risk management, or regulatory requirements (e.g., ECOA / Reg B adverse action).

Familiarity with MLOps platforms and model serving infrastructure.

Applied mathematics background - discrete mathematics, complex systems, and mathematical modeling.

Strong understanding of data structures and distributed systems for large-scale data processing, with an eye for efficient, scalable algorithm and code design.

What you'll own

Full-stack feature delivery across the borrower app and the Django API - most features span both.

Fintech integration work: new vendor APIs, reliable webhook handling, retry and reconciliation semantics, and payment and loan-servicing workflows.

Infrastructure evolution - growing with scale.

Raising the engineering bar: testing strategy, observability, performance, and security in a regulated lending domain.

Preferred

Experience designing and supporting the AI/data-science model lifecycle in fintech - from architecture and prototyping through to production-grade code and application integration, alongside the engineering team.

Credit risk, underwriting, or cash-flow modeling experience.

Familiarity with fair-lending, model-risk management, or regulatory requirements (e.g., ECOA / Reg B adverse action).

Familiarity with MLOps platforms and model serving infrastructure.

Applied mathematics background - discrete mathematics, complex systems, and mathematical modeling.

Strong understanding of data structures and distributed systems for large-scale data processing, with an eye for efficient, scalable algorithm and code design.

Qualifications

Strong TypeScript/React (Next.js App Router experience a plus) and strong Python/Django (including Django REST Framework) - this is a genuinely full-stack role.

Comfortable with PostgreSQL data modeling, Celery/queue-based async patterns, and third-party API integration at production quality (idempotency, retries, webhooks).

Working AWS knowledge (Beanstalk/EC2, RDS, SQS) - enough to own deploys and debug production.

Strong familiarity with Git, CI/CD pipelines, and automated deployment.

A testing habit - you write tests without being asked (Vitest / Testing Library, Playwright, pytest).

Strong command of AI coding tools, with disciplined verification and data-privacy guardrails.

Excellent documentation skills and a commitment to organized, understandable code that scales as the team grows.

Care about correctness with money movement.

Curiosity about fintech and empathy for users - you're passionate about building technology that solves real-world financial challenges.

Founding-engineer temperament: owns problems end