6 of the Best API Testing Tools in the Market

6 of the Best API Testing Tools in the Market

In this article, see six of the best API testing tools available on the market, including Katalon Studio, Postman, SoapUI, Tricentis Tosca, JMeter, and Rest-Assure. API test is a significant part of a successful Continuous Integration/ DevOps practice.

API test is a significant part of a successful Continuous Integration/ DevOps practice. As per Google Trends, the interest in Web/ API services tests has been progressively growing over the few decades. According to SmartBear research over 3,372 software professionals in API test over 2019, 91 percent of participants either presently have, or thinking to have a formal API test procedure in place in the coming future. Around 45 percent of API testers reported that their company already automated 50% or more of test projects. Moreover, by more than 75 percent of companies across industries, API quality is considered a top priority.

With APIs more and more becoming crucial elements for software development, it has become critically essential for programmers and developers to carry out API testing. API test is a procedure that concentrates on identifying whether an API that has been developed meets up the expected threshold concerning security, reliability, performance, and functionality. As these tests are crucially vital, you need to make use of the top API testing tools out there.

Major Points to Consider for API Tests:

• API consumer or Target Audience

• Test for normal situations

• Testing aspects

• The surroundings in which the API is going to be used

• Tests for negative tests or abnormal conditions

Why Execute API Testing?

As more and more companies make the shift left toward continuous deployment (CD), continuous integration (CI), and DevOps, test feedback requires being faster than ever. Concentrating completely on User Interface automation which is particularly time-consuming could kill your automation testing efforts. As you scramble to ensure that your apps are prepared to ship, API tests must be a component of your complete automation strategy.

APIs are the base of new and advanced software development, as more and more teams move away from monolithic apps and start adopting a microservices technique for software development. Through microservices that are making up the backbone of most modern development efforts, API tests turn out to be even more crucial than before.

Top 6 API Testing Tools Available on the Market

Because of the API test’s nature, it cannot be manually tested, and we have to go for some best of the API test tools to tests APIs. Here, I have compiled a list of the top API testing tools in the market.

  1. Katalon Studio
  2. Postman
  3. SoapUI
  4. Tricentis Tosca
  5. JMeter
  6. Rest-Assured

1. Katalon Studio

Katalon Studio

Katalon Studio is an open-source, comprehensive, and robust test automation tool API, Web app testing, Desktop testing, and Mobile app testing. The key benefit of using Katalon studio is its capacity to combine business levels (API/ Web services) and UI for multiple operating systems like Mac OS, Linux, and Windows. Katalon Studio supports RESTful and SOAP requests with several kinds of commands like DELETE, PUT, POST, with parameterized capacity.

Katalon Studio gives easy deployment by comprising all plugins, and ALM integrations, frameworks in one package. Besides being an open-source solution, Katalon also provides paid support services for enterprises, businesses, and small teams. It is also named as the Gartner Peer Insights Customers’ Choices 2020 for Software Automation Testing.

Key Features:

  • Supports both SOAP and RESTful requests with multiple types of commands like DELETE, PUT, GET, POST, with parameterized ability
  • Capacity to combine API and User Interface verification
  • Many built-in keywords for creating test cases
  • Supports a data-driven method
  • Support the most influential assertion libraries, AssertJ for creating fluent assertion with Behavioural Data-Driven style.
  • Used for automation tests as well as exploratory tests
  • Suitable for both beginners and experts with the Manual and Scripting modes
  • Suitable for non-techies, experts, and beginners with the Scripting and Manual modes

• Customizable and Pre-built code templates

• Auto-completion, auto-formatting, and code inspection features for the code


  • Does not have support for distributed tests

Official Website: Katalon Studio

2. Postman


It is a collaboration platform for Application Programming Interface development. It is one of the most popular API clients. *Postman *enables us to plan, build, share, allocate, test, & document APIs. Originally postman was only a Google Chrome plugin. At present, it extends its solution with the native versions of Mac and Window. If in case you do not wish to code then you can select Postman for your API test.

Postman is one of the best choices for API tests for beginners who do not want to dive under coding in an IDE (integrated development environment) using a similar language as the software developers. Starting from advanced version 7.3 in 2020, this amazing tool assists users in better manage the collections and API elements (monitors, mock server, tests, and documentation) created from API schemas by using the most modern preferences. The current version 7.31.1 for Linux, Windows, and Mac App has been released in Aug 2020 with slight bug fixes.

Key Features:

• Works on Windows, Mac OS, Linux, and Chrome applications

• Supports Continuous Integration/Continuous Delivery service with Newman

• Simple-to-use REST client

• Supports run, test, document, and monitor features

• The rich interface that makes it simple to use

• Can be used for both exploratory and automated testing

• Supports RAML & Swagger formats

• No requirement to learn a new language

• Allow users to simply share the information with the team as they can wrap up all the requests and possible responses, and then send it to their teammates


• Even though the company version is easy to install and use, it comes with restricted requests

• Pricing for business is too high

*Official Website: *Postman

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How to Do API Testing?

API endpoint when you send the get request to that URL it returns the JSON response. In this article, I am going to use postman assertions for all the examples since it is the most popular tool. But this article is not intended only for the postman tool.

A Simple Guide to API Development Tools

APIs can be as simple as 1 endpoint for use by 100s of users or as complex as the AWS APIs with 1000s of endpoints and 100s of thousands of users. Building them can mean spending a couple of hours using a low-code platform or months of work using a multitude of tools. Hosting them can be as simple as using one platform that does everything we need or as complex as setting up and managing ingress control, security, caching, failover, metrics, scaling.

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