Complete Guide to API Integrations for Modern Web Applications

Map the integration contract

Document endpoints, request and response schemas, authentication, error codes, rate limits, and ownership. A written contract prevents hidden assumptions between systems.

Protect every request

Use HTTPS, short-lived tokens where possible, least-privilege credentials, and secret rotation. Validate incoming data at the boundary and never log access tokens or payment details.

Design for failure

• Use timeouts and bounded retries with exponential backoff.
• Make writes idempotent so retries cannot duplicate actions.
• Queue slow or unreliable partner calls.
• Record correlation IDs and useful, privacy-safe error context.

Webhooks and operations

Verify webhook signatures, store event IDs, process events asynchronously, and provide replay tooling. Monitor latency, error rates, and quota usage so issues are found before customers report them.