What is API Integration?

API integration connects two or more software systems through defined interfaces so they can share data and trigger actions. The goal is to move information from one system to another without manual copying, while keeping the flow controlled and observable.

For example, when an e-commerce order is placed, inventory can be updated, a shipping label can be created, an accounting entry can be prepared, and customer data can be sent to a CRM. Each step may run through an API call or event notification.

Design Considerations

Authentication: API keys, OAuth2, JWTs, or signed requests
Data mapping: Field names, currency, time zone, and status-code conversion
Error handling: Retries, idempotency keys, and partial-failure scenarios
Synchronization model: Real-time API call, scheduled polling, or event-based notification
Observability: Logs, metrics, and correlation IDs for troubleshooting

Business Use

API integrations are common with payment providers, ERP, accounting, CRM, warehouse, shipping, and marketplace systems. A webhook can notify a system when an order is created; for critical flows, queues and retry logic reduce data-loss risk.

A good integration is more than a connection that works once. Version changes, quota limits, support processes, and test environments need to be planned early, otherwise the production workflow becomes fragile.