One integration layer, four systems: a Kumasi retailer closes month-end in a day

The problem

POS, inventory, accounting and e-commerce each ran in their own tool. Month-end reconciliation took five days and three people.

What we did

We built a lightweight middleware layer in Node.js with event-driven syncing between all four systems, added an ops dashboard, and trained the finance team to self-serve.

How we delivered it

1. Step 1Process mapping

   Documented every manual handoff between the four systems.

2. Step 2Event design

   Chose an event bus pattern so each system stayed the source of truth for its own domain.

3. Step 3Connector build

   Four connectors, each with a dead-letter queue and retry policy.

4. Step 4Parallel run

   Ran old and new reconciliation in parallel for one full month.

5. Step 5Handover

   Ops dashboard and a half-day workshop with the finance team.