API Response Time Higher in Katalon Compared to Postman

Web Testing
1

I am observing a significant difference in API response times between Katalon Studio and Postman for the same API.

  • Postman response time: ~1.8 seconds

  • Katalon response time: ~4.1 seconds

Both requests are executed with the same endpoint, payload, and under similar network conditions. However, Katalon consistently takes almost double the time.

I would like to understand:

  • Why there is a delay when executing APIs in Katalon

  • Whether Katalon adds any internal overhead (logging, reporting, execution engine, etc.)

  • How to accurately measure API performance using Katalon

2
  1. The API is not slower in Katalon
  2. You’re seeing framework overhead, not actual API delay
  3. Use response.getElapsedTime() for fair comparison
  4. Use dedicated tools if performance testing is your goal
3

What do you mean?

Do you mean

  1. the target URL responds the same to Katalon and Postman, but
  2. Katalon Studio is slower than Postman in sending a request and digesting a response

You should speak more clearly.

4

Framework overhead means→ The extra time added by Katalon itself ( the tool + execution engine), not by the API server.

So total time ( Katalon) = Actual API Time + Katalon Processing Time

5

I would recommend you not to use Katalon for API testing.

6

I would rather write a bash script (or a python script) that calls curl for minimum overhead.

I don’t have any hands-on experience of Postman, but as far as i read their doc, it looks good.

7

I am using Katalon for API testing, it is good only not that much bad. We cannot definitely compare to Postman or other API tools, but it is manageable.

But you are right, if someone dedicatedly need for API testing then surely it is not a recommended tool.

8

I think, the API testing feature of Katalon Studio is bogus. Let me show you an example, see

It does not support any binary data in the HTTP response: such as images, pdf, xlsx, zip, tar, mp4, etc. It naively assumes that a HTTP response carries text only (json, xml, text/plain). Terrible, isn’t it.

As far as I see, Katalon is no longer investing their human resources into the API testing features. AI would not cure the poor implementation of the product. I would expect no improvement in future.

9

Kudos to your technical expertise

10

Yes , Postman is much faster than Katalon as let just say postman is a lightweight and much faster tool than katalon