What Is an API-Based Integration?

An API (application programming interface) is a documented way for one program to ask another to do something — return a list of orders, create a product, update a stock level. An API-based integration connects systems exclusively through these interfaces.

How it works

1. Authenticate. The integration proves its identity, typically with an access token, an API key, or an OAuth flow.
2. Call an endpoint. It sends a request (for example, “get orders updated since 10:00”).
3. Handle the response. It reads the data, follows pagination for large results, and checks for errors.
4. Respect limits. It slows down when the API signals that rate limits are near.

Common API styles

Style	Characteristics	Seen in
REST	Resources at URLs, HTTP methods (GET, POST, PUT, DELETE), JSON bodies	WooCommerce, BigCommerce, Adobe Commerce, most ERPs
GraphQL	One endpoint; clients specify exactly which fields to return	Shopify Admin API, Adobe Commerce (storefront-oriented)
SOAP	XML messages with a formal contract (WSDL)	Older ERPs, Adobe Commerce
File-based	CSV/XML exchanged via SFTP or folders	Legacy ERPs, batch imports

Why APIs are preferred

• Business rules stay in force. The ERP validates data and runs its logic when records arrive through its API.
• Stability. APIs are versioned contracts; database schemas are internal and can change without notice.
• Security. APIs can grant narrow permissions; database access is usually all-or-nothing.
• Auditability. API calls can be logged and attributed.

Practical concerns

• Versioning: platforms release new API versions and retire old ones. Shopify, for instance, releases quarterly versions supported for at least 12 months.
• Rate limits: each platform limits usage differently — request counts per window, or calculated query cost.
• Pagination: large result sets come in pages; integrations must follow cursors or page numbers.
• Errors: some APIs (including GraphQL APIs) can return HTTP 200 with errors in the body, so status codes alone are not enough.
• Idempotency: creates must be safe to retry; see idempotency.

APIs and webhooks together

APIs are request-driven: you ask, they answer. To learn about changes without constantly asking, platforms also offer webhooks. Most integrations combine both — webhooks to learn something changed, APIs to fetch the details and write results.

Summary

API-based integrations connect systems through documented, versioned interfaces that preserve business rules and permissions. They require handling of authentication, pagination, errors, rate limits, and version changes, and they work best combined with webhooks for change detection.