Production Backend Engineering Project

E-Commerce Backend System

Designed a backend commerce API around real purchase flows, authorization boundaries, and data integrity.

Problem statement

Modeling commerce workflows is mostly about handling edge cases: permission checks, inventory assumptions, order transitions, and keeping endpoints coherent as the system grows.

Architecture breakdown

I approached it as a production API with explicit resources, role-aware authorization, and service-oriented abstractions for catalog, cart, and checkout concerns.

- Token-based authentication and role-aware authorization
- Product, cart, and order domains separated into composable services
- Relational schema design optimized for checkout and order history workflows
- RESTful resource design with validation and predictable status handling

Tech stack explanation

JavaSpring BootPostgreSQLJWT AuthReactREST APIs

System diagram

[ Client Apps ]
      |
      v
[ Auth Layer ] ---> [ User Roles ]
      |
      v
[ API Gateway / Routes ]
      |
      +--> [ Catalog Service ] ---> [ Products DB ]
      +--> [ Cart Service ] ------> [ Cart Tables ]
      +--> [ Order Service ] -----> [ Orders + Payments ]

Key challenges

A backend-only commerce platform focused on clear domain boundaries, predictable API behavior, and a schema that supports catalog, cart, and order lifecycles without coupling everything into a single service layer.

- Demonstrated production API design rather than CRUD-only endpoints.
- Showed how backend architecture can stay extensible as business logic grows.
- Created a portfolio piece that speaks directly to scalable backend engineering.

What I learned

Good API design is less about endpoint count and more about preserving domain clarity.

Schema design becomes the foundation for workflow flexibility later on.

Authorization needs to be treated as part of architecture, not an afterthought.