Backend Engineer, API

Pylon • San Francisco, CA

2d • Onsite

About The Position

About Pylon
America’s $13T mortgage market is one of the most important financial systems in the world. It underwrites the middle class and is the mechanism through which millions of families build wealth. But while every other financial instrument has been simplified to an API call, mortgages are still assembled by hand.
We started from zero and created the first vertically integrated mortgage platform that turns origination into a single API.
Publicly traded companies and the country’s largest originators are already building on Pylon. Revenue is compounding monthly. We’re backed by Peter Thiel, Conversion Capital, QED, Citi, Fifth Wall, and the founders of Ramp, Blend, and Mercury.
Working at Pylon isn’t for those seeking comfort. The people who thrive here have high agency, strong opinions, and a track record of delivering outcomes without direction. Many of us are former founders. We move quickly, challenge each other directly, and take full ownership of results. It’s hard work, but it will be worth it.
Join us in building America’s mortgage rails.
The Team
We're looking for Back End Engineers to join our API team. We treat our GraphQL API as a product — because it is one. Multiple customers build directly on top of it, and the quality of their experience is determined by how well we design, document, and maintain it.
Mortgage is a surprisingly rich domain to model. It's path-dependent: the choices you make early in a loan constrain what's possible later. It's nonlinear: different borrower situations branch into wildly different flows. Most APIs in this space paper over that complexity. We're building one that embraces it — encoding the real shape of mortgage into a surface that's impossible to misuse and delightful to build against.

Responsibilities

• Define what a mortgage is in code. Seriously. You'll work on semantic models that don't just represent mortgages as they exist today — they expand what a mortgage can be. This is product design at the API layer.
• Build toward an event-driven API. We're moving to a world where our API doesn't just respond to requests — it tells you what happened, why, and what you can do next. You'll help design and ship that future.
• Make the complex feel simple. Our API should make the mortgage process impossible to get wrong. That means thoughtful abstractions, clear documentation, and an obsessive focus on developer experience.
• Design for nonlinearity. Mortgage flows aren't linear wizards. Our future API encodes choice, branching, and path-dependence natively. You'll work on guided experiences that model real-world complexity without exposing it as chaos.
• Treat this as a product surface. You'll think about breaking changes, versioning, onboarding, and the full lifecycle of an API that real companies depend on.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level
• Education Level: No Education Listed