API integrations are often described as simple connectors. In practice they define how reliable your software feels: whether orders sync, whether inventory matches, and whether support teams trust the data on screen. Good integration planning happens before development starts, not after the UI is finished.
Map systems and data ownership
List every system that sends or receives data: accounting, warehouse, CRM, payment provider, logistics partner, or legacy desktop tool. For each one, identify which system is the source of truth for customers, products, prices, stock, and invoices.
Disputes over source of truth cause the most integration rework. Resolve them in workshops with business and operations stakeholders, not only with developers.
Define events and failure behaviour
Integrations should be described as events: order created, payment confirmed, shipment dispatched, customer updated. For each event, specify direction, frequency, retry rules, and what happens when the remote system is unavailable.
Users need clear failure behaviour. Should the app queue the action, show a warning, or block the step entirely? The answer depends on business risk, not only on technical convenience.
Security and observability
Use least-privilege credentials, rotate keys where possible, and log integration activity in a way support teams can understand. When something fails at night, logs should show which record, which endpoint, and which response caused the problem.
Well-planned integrations reduce manual reconciliation and make future modules easier to add because the data layer is already structured.