API Integration Checklist: 10 Questions to Answer Before You Connect Your Systems

Integrating business systems promises a lot: no more copying data between tools, faster processes and fewer mistakes. But integrations that are rushed often create new problems — duplicate customers, orders that silently fail to sync, or API keys left in places they should not be.

Before you start, work through these ten questions with your team and your development partner.

1. Which system is the source of truth?

For each type of data — customers, products, prices, stock, invoices — decide which system owns it. If two systems can both edit the same record, define how conflicts are resolved. Most integration headaches start with unclear ownership.

2. What should trigger a sync?

Should data move the moment something changes (usually via webhooks), on a schedule, or when a user takes an action? Real-time sync feels better but is more complex; a scheduled sync every few minutes is often good enough and easier to recover from.

3. How will records be matched?

Decide how a customer in your website database is matched to the same customer in your CRM. Email addresses change and names are not unique, so store each system’s ID against the record once it has been linked.

4. What happens when the other system is down?

Every external service will be unavailable at some point. A good integration queues work, retries with increasing delays, and avoids creating duplicates when a retry succeeds. Ask what happens to an order placed during an outage.

5. Are the API limits compatible with your volume?

Most APIs limit how many requests you can make per minute or per day. Check the limits against your busiest periods — a sale, the end of the month — and design batching or caching if needed.

6. How are credentials stored and scoped?

API keys and tokens should live in environment configuration or a secrets manager, never in source code or front-end JavaScript. Use the narrowest permissions the provider allows, and plan how keys will be rotated if a team member leaves.

7. What personal data will move, and where?

Integrations often copy personal data into new places. Map what is transferred, make sure it is needed, and check that each provider’s data handling fits your privacy policy and your obligations under applicable laws, such as India’s Digital Personal Data Protection Act.

8. How will you know when something breaks?

Log every request that fails, and alert a named person when errors pass a threshold. A simple daily summary of synced and failed records catches problems before customers notice them.

9. How will you test without touching live data?

Use the provider’s sandbox or test mode where one exists, and test the unhappy paths: invalid data, timeouts, duplicate webhooks and expired credentials — not just the case where everything works.

10. Who maintains it after launch?

APIs change. Providers deprecate versions, add required fields and alter rate limits. Agree who watches for these notices and who updates the integration, and make sure the integration is documented well enough for someone new to understand it.

Start with the flow, not the code

A one-page diagram showing each system, what data moves between them and what triggers it will answer most of these questions — and it is the best brief you can give a developer. Time spent here is repaid many times over in a reliable integration.