Not all bugs live in your codebase. Some are hiding in the APIs you never wrote — but rely on every day.
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Hidden Dependencies, Visible Failures
We tend to treat API testing as a box-checking exercise — hit the endpoint, assert the response, move on. But in today’s distributed systems, many of the APIs our systems depend on aren’t ours at all.
Think about it:
Authentication via OAuth providers
Payments through Razorpay, Stripe, or PayPal
Product info from third-party catalogs
CDN-hosted image services or geo-location APIs
Even internal APIs from other teams in your org
You don’t control the code, but you do depend on the contract, uptime, rate limits, and even their quirks.
Why You Should Be Testing Them Anyway
Just because the API isn’t under your repo doesn’t mean you can skip testing it. If it breaks, your users blame you, not the third-party vendor.
Here’s where things go wrong:
Rate Limits Misfire: One spike and you’re throttled. Did you test your fallbacks?
