What is an API integration, and what actually breaks in one?
August 8, 2026 1 min read
It is your system talking to somebody else's over the internet. What breaks is never the happy path — it is the timeout, the retry, the field they changed without telling you, and the day their server is down and yours has to keep trading.
The four failures to design for
It is slow. Your checkout must not hang for thirty seconds because a courier API is thinking; the call belongs in a background job.
It answers twice. Every request that changes money or stock needs an idempotency key, or a retry becomes a duplicate.
It changes. Fields get renamed and versions get deprecated, usually with an email nobody read. Log the raw response so you can prove what arrived.
It is down. Decide in advance whether you queue and continue or stop and tell the user. Both are valid; having no answer is not.
What we insist on
Retries with backoff, an idempotency key on anything that writes, the raw payload stored, and logs a person can read at 2am. That last one sounds soft and is the difference between a ten-minute fix and a lost day.
