🤖 "Postman Can’t Automatically Validate A Response Structure"? Here’s How It Can!

[danny-dainton]

Background: Community Feedback
This post was inspired by a comment from @navneeet in a previous weekly challenge, suggesting that Postman should go beyond checking for 200 status codes and also validate the structure of API response data.

See the community feedback and problem context

@navneeet

Here’s what annoys me: An API that was working fine yesterday suddenly returns slightly different data today. Maybe a field got renamed from user_id to userId, or an array that used to return 10 items now caps at 5, or timestamps switched from Unix to ISO format. The backend team “forgot” to mention it, and now I’m debugging phantom failures.

What I desperately need is Postman to remember the “shape” of successful responses and automatically flag structural changes. Not just status codes but even the actual response anatomy.

For example: Every time I get a 200 OK, Postman quietly fingerprints the response structure. Next time I run the same request, it compares:

• Did any fields disappear or get renamed?
• Did data types change? (string → number, object → array)
• Did array lengths drastically change?
• Did nested structure shift?

When something changes, instead of a cryptic test failure, I should get: “Hey, this endpoint’s response structure changed since last Tuesday. Field ‘created_at’ is now ‘createdAt’ and the ‘metadata’ object moved inside ‘data’.”

This would turn hours of “why is this broken now?” into seconds of “oh, they changed the API again.”

Watch the Workflow in Action
In this five-minute walkthrough, I’ll show you how to use Postman’s built-in tools and also the Zod NPM package to bring schema validation into your collections. By validating your request and response structures, you can catch errors sooner, enforce consistent data standards, and make your testing process far more robust.

---

Did this help you out? Tell us in the comments!

And if there’s another Postman topic you’d love a quick walk through on, let us know