5 Best API Testing Tools in 2024

Dec 7, 2022

isographic of developers using the best api testing tools

At the center of our modern, highly interconnected digital world you will find APIs. 

Application Programming Interfaces, or APIs, allow two software systems to communicate and exchange data with one another. In practice, this exchange might look like sending an instant message, checking a website for local restaurant reviews, or searching for a friend on social media. 

Once you send a request online, exchanges of information happen simultaneously between applications, databases, and devices, and you are returned a result. Occasionally, however, you might end up waiting a long time for a result, or the result isn’t at all what you were looking for. This is where API testing tools come in.

What is API Testing in 2024?

API testing is the process of software testing an API for functionality, reliability, performance, and security. This testing process is carried out within the Business Logic layer of an application and is critical for ensuring APIs properly execute their intended functions. 

Although the API testing process can be done manually, given the need for fast and accurate program development – using an automated API testing tool is a wise decision. 

We’ve compiled a list of the best API testing tools on the market so you can spend less time in 2024 scouring the web, and more time building critical software.

Best API Testing Tools for 2024


Postman is a platform for building and using APIs. Initially a Google Chrome plugin, Postman has expanded to include Windows, Mac, Linux, and a web browser version. This tried and trusted API testing tool simplifies the API lifecycle and streamlines collaboration through a built-in workstation. 


  • Easy-to-use platform supports various operating systems.
  • Services allow developers to test, mock, monitor, perform debugging, run requests, and more.
  • Supports various formats such as Swagger and RAML.
  • Good for manual testing.


  • Free version has limited features.
  • Limited integration capabilities.


Katalon Studios is a robust automated testing tool designed to house and reuse test scripts for UI and Business level phases. This API testing tool supports both SOAP and REST requests and is run on a Selenium-based engine. 


  • Framework supports seamless CI/CD integration.
  • Dual scripting interfaces accommodates developers of all levels. 
  • Data driven approach enables end-to-end API testing. 


  • Only supports Groovy, a Java-based scripting language.
  • Does not currently support distributed testing.
  • Not open source.


Appsurify TestBrain is a risk-based testing tool that plugs into existing QA practices allowing teams to automatically run only the API tests that have been impacted by recent developer changes for 10x faster test results and optimizes CI/CD pipelines so builds pass on time and with confidence. TestBrain finds bugs faster with automated and manual testing capabilities. 


  • Instant feedback from lengthy automation testing. 
  • Plugs into existing test practices and works with any test framework i.e. API Tests. 
  • Accelerates and stabilizes active CI/CD Pipelines.
  • Risk map for manual testers.


  • Must have existing QA practice/frameworks in place.
  • Automatic Risk Based Testing model takes time to train.


SoapUI is a software entirely dedicated to API testing. SoapUI’s SmartBear testing tools make it easy to create, manage, and execute end-to-end tests on REST, SOAP, & GraphQL APIs, JMS, JDBC, and other web services. This software’s free version is open source and easy to use, making it a top choice for developers of all budgets. 


  • Point-and-click and drag-and-drop features. 
  • Supports customized reports in various formats.
  • Allows for data-driven and asynchronous testing. 


  • Low stability, slower run times reported.
  •  Software lacks documentation.

API Fortress

API Fortress, now part of SauceLabs, is a continuous testing solution for APIs that tests functionality, load, and performance. A versatile API testing platform that you can leverage to produce and automate functional tests, perform load tests, and virtualize APIs. Supports Restful and GraphQL.


  • Automate tests as part of the CI pipeline.
  • Intuitive UI that is easy to use for any skill level.
  • Support Test REST, SOAP, GraphQL, Web Services, and Microservices


  • Not all features of API Fortress are offered to the cloud users
  • It’s not straightforward to test local APIs (requires running an agent)
  • Can be expensive for small teams.

Find the Right API Testing Tool in 2024

This list is just a glimpse into the vast array of API testing options available. Every API testing tool you come across will have different features and levels of accessibility, so it’s best to try a few options and see what’s best for your testing needs.

If you already have a testing practice in place and are looking for accelerated test times and streamlined results, TestBrain might be the right API plug-in tool for you. Talk to the Appsurify team for a consultation or to request a free trial.