Payments and Inventory: The Engine Room of E-commerce

Payments and Inventory: The Engine Room of E-commerce

This is a description of a project type we work on: the half of a store that customers never see, and that decides whether the business can trust its own numbers.

The Challenge

Stock was updated in one place and sold in another, orders moved through states tracked by email, and reconciliation between the payment provider and the internal records was a manual monthly exercise. Every sale increased the chance of overselling or of an order nobody had picked.

Our Approach

Discovery documented the full lifecycle of an order and of a unit of stock: every state, every actor, and every system that needs to know when a transition happens. Then the hard question: which system is the source of truth for each fact, and what happens when two disagree.

Solution

Inventory held in one model with explicit reservations, so a quantity is either available, held or sold, never both. Orders move through defined states with the transitions recorded, payment status arrives through webhooks that are verified and idempotent, and a reconciliation view surfaces anything that did not line up.

Technology

A relational database with transactions where correctness matters, a queue for the work that must not be lost, and integration adapters isolating each third-party service behind a small interface.

Implementation

Rolled out with reconciliation running in parallel with the old process until the numbers matched consistently, then cut over with monitoring on the failure paths.

Results

Overselling, reconciliation effort and order-handling time are measured against the pre-project baseline, and published only where verified and approved.

Need the engine room rebuilt? Tell us about your project and we will start with the order lifecycle.

Project details in this article are deliberately general. Client names, verified results and references are published only with the client's approval.