Rebuilding a live marketplace backend

How I changed the foundations of a live marketplace backend while the product team continued shipping.
Client
BUMP
Date
Service
Product and technology leadership
Role
First engineer on a new full-stack team

What changed

  • Mapped live product flows before changing the architecture.
  • Introduced clearer service boundaries around the existing mobile product.
  • Helped establish the working practices for an in-house engineering function.

Context

BUMP had a live sneaker and streetwear marketplace whose Parse.js backend was concentrated in a single file. Mobile product work was continuing, so treating the system as a clean rewrite would have ignored the real delivery risk.

My remit

I joined as the first engineer on a new full-stack team. My remit covered the backend transition, order-flow design, delivery practices and support for building the engineering function.

Decisions and delivery

  • Mapped authentication, inventory, payment and verification flows before separating the code.
  • Introduced a typed NestJS and GraphQL backend in stages around the existing mobile clients.
  • Used a CQRS-based order model for the long-running payment, verification and shipping states.
  • Added tests, reviews and clearer delivery practices while product work continued.
  • Supported role definition, interviews and team planning as the internal engineering function formed.

Outcome

The work moved a concentrated backend towards clearer boundaries and gave the team a more maintainable basis for continuing product delivery. It also joined architecture decisions with the practical work of establishing an engineering function.