API Integrations

What To Know

API integration is one of the strongest signals in the FDE listings. The practical skill is not just "call an API." It is getting two real systems to cooperate through messy data, authentication, error handling, and customer expectations.

Core Concepts

• REST resources and endpoints.
• API keys, OAuth, scopes, and secrets.
• Pagination and rate limits.
• Webhooks and event-driven updates.
• Retries and backoff.
• Idempotency.
• Data validation and transformation.
• Audit logs.
• Sandbox vs production credentials.
• Go-live checklist.

Common Failure Modes

• Auth works in sandbox but not production.
• Customer data does not match the documented schema.
• Duplicate events create duplicate records.
• Webhooks arrive out of order.
• Rate limits break bulk imports.
• Error messages are too vague for operators.
• No one knows who owns a failed record.

Interview Angle

Strong phrasing:

I think about integrations as operational systems, not just API calls: auth, data shape, retries, ownership, go-live, and troubleshooting all matter.