Before Building an API Integration: Seven Architecture Decisions

Define the source of truth for every entity: customer, item, order, or balance. If two systems may edit the same truth without a rule, conflicting copies appear.

Use a stable cross-system identifier and define create, update, and delete semantics. A name or display number is not always a safe integration key.

Choose real-time or batch movement, acceptable delay, and duplicate prevention. Retry must be idempotent so it cannot create an order or invoice twice.

Build monitoring that shows message, state, error, attempt count, and required action, with appropriate access, secrets, and logging. Test failure as thoroughly as success.