Common Challenges in API Testing with Katalon

Let’s be honest—API testing isn’t always smooth, even with popular tools like Katalon.

Katalon Studio has become a popular tool for API testing due to its:

• ease of use, out-of-the-box functionality, and support for multiple automation frameworks.

While Katalon offers a user-friendly interface and strong features, it’s not without its pain points

However, like any tool, Katalon has its own limitations and challenges specific to API testing. Let's dive into some of the most common challenges and, more importantly, how to overcome them.

Let’s get started:

1. Limited Flexibility with Assertions

The Problem:

While Katalon offers built-in assertions for checking API response codes and simple key-value pairs, it lacks advanced features for handling complex response structures like deeply nested JSON or XML objects. For more sophisticated validations, such as dynamic content in API responses, the built-in assertions might not be enough.

Why It’s a Problem:

When testing APIs that return large, deeply nested JSON objects or complex XML structures, you might need to perform validations on multiple levels or verify dynamic data that changes with each call. Katalon’s assertion methods often require custom scripting, which defeats the purpose of using a tool designed to reduce manual coding.

How can you solve this?

HyperTest, with its AI-driven automation, can automatically generate and validate complex response structures without the need for extensive custom scripting. This reduces the time spent on manual test creation and simplifies handling complex data types.

2. Poor Handling of Dynamic Data in Requests

The Problem:

Many APIs require dynamic data inputs—like tokens, timestamps, or user IDs—that change frequently or vary with each test run. While Katalon provides some capabilities to manage dynamic data through test variables, it lacks seamless solutions for handling dynamic data across a suite of API tests.

Why It’s a Problem:

Users often struggle to automate API tests where inputs need to be updated dynamically from one test to another, such as refreshing authentication tokens or passing IDs retrieved from a previous API call. In such cases, you might need to write custom scripts to automate this process, which can increase complexity and maintenance overhead.

How can you solve this?

HyperTest excels at managing dynamic data like tokens, session IDs, and time-sensitive parameters. It can generate integration tests based on real-time traffic, meaning you don’t need to constantly update or refresh data manually as you might with Katalon. This minimizes the maintenance burden.

3. Complex Authentication Handling

The Problem:

Although Katalon supports basic authentication mechanisms like Basic Auth and API keys, handling more complex authentication flows—like OAuth 2.0, JWT tokens, and SAML—is not as straightforward. The tool lacks built-in support for automating the entire authentication flow (e.g., retrieving tokens, refreshing them, and injecting them into subsequent requests).

Why It’s a Problem:

APIs that rely on OAuth or JWT-based authentication require continuous updates to tokens or session IDs. Katalon users often need to create custom scripts to fetch tokens manually, refresh them, and pass them into API headers. While Katalon supports chaining API requests, the process of automating this across multiple test cases can be cumbersome, especially when dealing with frequent token expiration.

How can you solve this?

For complex authentication mechanisms such as OAuth or JWT, HyperTest streamlines the process by automatically managing token generation and handling session states. This eliminates the need for custom scripts or manual token updates, which can be tedious in Katalon.

4. Steep Learning Curve for Advanced Customization

The Problem:

Katalon is marketed as a tool for non-developers and manual testers transitioning to automation, but its flexibility is limited for more advanced API testing scenarios. Once you get beyond the basics, the tool requires significant scripting in Groovy to handle complex test cases, making it less accessible for non-technical users.

Why It’s a Problem:

Teams that adopt Katalon for its ease of use often find themselves grappling with Groovy scripting when they need to implement more advanced features like custom assertions, API response parsing, or request chaining with dynamic data. For testers without coding skills, this can be a significant barrier, making them dependent on developers to write or troubleshoot scripts.

How can you solve this?

Developers' set-up our SDK (2-lines) across any of their (backend) services and configure it to record traffic from any environment. When HyperTest works in RECORD mode it collects end to end trace of every incoming request i.e. the request, response and outbound calls.

These requests (tests) can be replayed on a new build later to check for regressions in API responses and outbound calls. In the REPLAY mode HyperTest uses mocked responses of all dependent systems to keep tests non-flakey and results deterministic and consistent.

HyperTest (2-line SDK) auto-instruments all key functions and methods across all libraries you can use to make outbound calls. This helps HyperTest mock these calls in REPLAY without asking developers to make any change in their source code.

Final Verdict

Watch this demo and see how we're making things easy for devs:

Make sure to check-out our other content assets in this series, it will help you in deciding why HyperTest and why not "Katalon":

➡️Top 5 Katalon Alternatives and Competitors

➡️Katalon vs HyperTest: The Right API Testing Tool For You