Have you ever experienced an API integration where the production environment is different from the test environment?

As a Software Engineer, i have integrated a lot of third party APIs. Some were great some are okay and some were frustrating

We were tasked to integrate a large, well established company API and the documentation is fine, we built the integration in their test environment and It worked and signed the UAT and then we moved to production

then everything broke because the production API behaved completely differently from the test environment

Response keys are different,
Naming convention changed between endpoint
Error message were inconsistent

We had to rework more than 50% of our integration, and it it isnot because we made mistake in our integration but because the API itself was inconsistent across environments TEST and PROD

Im sharing because this taught me something important about how software should be built and have a rule

Test environments should mirror production, i mean if your test environment is 70% different from production, what exactly are you testing?

Internal consistency matters. Having one endpoint return "token", another return "accessToken", and another return "Token"

So if you're integrating an API and something feels off trust your instinct Test everything and compare environments

To the developers behind that API (if you ever read this) I genuinely hope you take this as feedback from someone who wants your product to be better. Because when it works, it works well

Have you ever experienced an API integration where the production environment felt like a completely different platform from the test environment? How did you handle it?

✍️ Usama