Four systems, one source of truth.

Reevia’s customer ran on four systems that each believed they were correct: clinic management, billing, a warehouse of historical records, and a spreadsheet somebody maintained by hand. Reporting never reconciled, and nobody could answer a simple question about a customer without opening three tabs.

The first decision was not technical. Source of truth was assigned field by field, in writing, before any code: legal name from billing, contact phone from the clinic system, status from the spreadsheet. Where no system owned a field, the integration flags instead of guessing.

Matching runs on tax ID, then normalized email, then digits-only phone. A single weak match goes to a review queue rather than a silent merge. Every value written to HubSpot carries its source and timestamp, so any figure can be traced back in seconds.

Over two million records now flow into one view, with a sync that completes in under fifty seconds and runs unattended. It reached production in four weeks, and it was the first time the business had cross-system visibility at all.