The API Integration Checklist We Use on Every Project

API integrations account for about 40% of our project work. After enough projects, patterns emerge. Here's the checklist we run through before writing integration code.

Before you write code

• •[ ] **Read the full API docs** - not just the endpoint you need, but auth, rate limits, error codes, and webhooks
• •[ ] **Check rate limits** - will your usage pattern hit them? Do you need queuing?
• •[ ] **Test the sandbox** - never assume the docs are accurate. Hit the endpoints yourself.
• •[ ] **Map the data model** - how does their data structure map to yours? Where are the gaps?

During development

• •[ ] **Centralize API calls** - one service layer, not scattered fetch calls
• •[ ] **Handle errors explicitly** - every error code gets a specific handler, not a generic catch
• •[ ] **Implement retry logic** - transient failures happen. Exponential backoff with jitter.
• •[ ] **Log everything** - request/response pairs, timestamps, correlation IDs

Before going live

• •[ ] **Test with production-like data** - sandbox data is often cleaner than reality
• •[ ] **Set up monitoring** - alerts on error rate spikes, latency changes, and auth failures
• •[ ] **Document the integration** - what it does, how it's configured, and how to troubleshoot
• •[ ] **Plan for API changes** - version your integration layer so upstream changes don't cascade

The one thing most teams skip

Webhook verification. If the API sends webhooks, verify the signatures. Unverified webhooks are a security hole that's easy to close and dangerous to leave open.