Top 5 API Testing Tools in 2024: Detailed Review

The interest in API testing has been increasing over the past few years, which is not a surprise given that API was the fastest-growing data type in 2021 with a +21% growth. APIs are being used extensively in different industries, such as banking, telecommunication, and retail. To have APIs that:

• Function correctly,
• Have adequate security, 
• Provide desirable performance, 
• Developed within the budget,

API testing must be done. However, there are many API testing tools available. In this article, we will review the top 5 API testing vendors based on our data driven list. 

Executive summary of reviews 

 Sponsors are listed at the top

1-PULSE

Sponsored:

PULSE is an automated AI-based API testing tool developed by Testifi. PULSE can:

• Integrate with CI/CD pipeline,
• Enable shift-left testing,
• Decrease expense, cycle time & effort maintenance by 50%. 

Leading companies such as Amazon, Vodafone and BMW use Testifi services. 

The unique feature of Pulse is:

Test generation based on the documentation

PULSE automatically creates API tests according to the details of the API documentation. The steps required are:

1. Provide the documentation URL.
2. Provide the URL of your system.
3. Provide the authentication details. 

After completing these steps, PULSE will analyze the results validate the documentation and show the results in a user-friendly dashboard based on the:

• API tests,
• Errors identified.

2- Postman

Postman initially was a browser extension for API validation but now it has become a very well-known API testing and developing platform. Different types of API testing can be done on Postman such as :

• Fuzz testing,
• Penetration testing,
• Regression testing,

Postman offers many functionalities such as: 

External libraries

Many external libraries for testing can be used in Postman. The benefit of external libraries is that they provide access to functionalities that are not built in JavaScript.

Customizable visualization 

The request responses can be visualized in Postman directly using HTML, CSS, and JavaScript. Additionally, charting libraries can be imported and used in Postman, giving it a high level of customization. 

Postman API

Postman API allows the standard create, read, update, and delete(CRUD) functionalities on the data stored on your Postman account. 

3- SOAPUI

SOAPUI, which is supported by Smartbear, is an open-source API testing platform. SOAPUI offers the traditional API testing types but with unique features, for example :

Load testing 

SOAPUI API load testing tool provides:

Scriptless load testing

Written functional test cases can be modified with a few clicks to load tests, removing the need for writing and maintaining test scripts for many APIs.

Load testing templates 

There are different types of load testing that analyze the API under different circumstances. SOAPUI provides ready templates for different types of load tests that can be configured easily. ( see Figure 1)

Figure1. SOAPUI load test templates 

Scriptless Functional Testing

Functional testing can be done by simply dropping, dragging, and clicking. 

API mocking

Sometimes the components required for testing might not be ready or developed yet. A mock component can be used to start the effort for testing. Mocks can be used for :

• Identifying operations that need testing,
• Developing first test scripts,
• Planning test execution

Mocks can be used for both functional and non-functional testing. However, mocking is not a simulation so it has limitations on the types of tests that can be used, but it should be enough for starting the testing process. 

4- ACCELQ

ACCELQ is a vendor that utilizes no-code & cloud in API testing for achieving API test automation. Its unique attribute is: 

No code test automation

ACCELQ provides a platform where API tests can be developed without the need for writing complex syntax. This can be a good fit for QA teams that lack advanced knowledge in programming. ACCELQ Test automation can be done for: 

• Element identification,
• Data definition,
• Test case generation.

You can watch the following video for a guide on how to use ACCELQ for testing REST API:

5- Katalon 

Katalon is a quality management platform that provides API testing as part of their solutions. Their autocomplete feature enables easier scripting(see Figure 2). Additionally, the autocomplete feature alongside code inspections, debuggers, and dual interface can optimize the debugging and maintaining tests. 

Figure 2. Katalon autocomplete feature