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Most Popular Free & Paid API Testing Tools 2021

This article explores API’s and API Testing methods. API (Application Programming Interface) testing is a type of software testing that aims to determine whether the applications are error-free or not. Getting a response to a request is not the only test criteria but to ensure how well the API Performs under pressure. This is one of the reasons why automated testing is necessary with APIs. 


What is an API :

API stands for Application Programming Interface. API is an interface between two software components to communicate to each other or it is a script or program that can interact with each other. There are many APIs available and companies provide APIs externally that let users programmatically interact with their services (think Twilio, Stripe, or Plaid).

The most popular API Testing Tools that we will discuss in this article are



SoapUI is one of the functional testing tools that address API testing. It’s also available in a free package that allows users to gain source code and minimum features. The pro-package of SoapUI offers unlimited features and benefits. It helps create a rapid test with the help of the Drag and Drop option and Point-and-click option. Script reuse is another feature of the free package. Pro-package helps to make custom code efficiently. It allows testers to extract data from sources such as databases, customer interaction, files and more. It costs $659 per year.


Apigee is a cross-cloud testing tool that allows testers to get powerful features such as flexible deployment, AI-powered API monitoring, digital asset monitoring, micro-services management and more. Apigee helps testers to reduce error rates with its features. This API testing tool is available at $2500 per month.

3.Tricentis Tosca 


Tricentis Tosca is an API testing tool that tackles software testing brilliantly. It also features cloud migration, application delivery and digital transformation. Tricentis is codeless and automated so testers can feel easy with it. This API testing tool works on both enterprise apps and agile development applications. It helps to reduce costs, improves quality and increase software delivery.

4.API Fortress

API Fortress is another tool for testing APIs. It’s a good choice for REST, SOAP, web services, micro-services and GraphQL. It can monitor internal APIs without any interruptions. It’s available in two different forms as Hybrid and Hosted Cloud. API Fortress is easy to understand and it’s available for different costs $1500 to $5000 per year.


JMeter is free of cost software testing tool that helps to measure performance and test some web applications. It can test many protocol types, servers and various applications such as SOAP, REST, FTP, LDAP, Message-Oriented Middleware, TCP, Native commands, Java objects and more. It’s also considered one of the best API test tools in the market.

6.Karate DSL  

Karate DSL is a new API testing free tool. It helps to combine API test automation, UI automation, mocks and other performance testing into a single framework. No need for any coding knowledge to understand Karate DSL because it’s user-friendly.


Rest-Assured is an open-source test tool. Testing and validation both are difficult in the REST service, so testers require some powerful tools like Rest-Assured. It can perform very well and the new version comes with bug-free and compatible features so benefits are guaranteed. Users no need high-technical knowledge to perform API testing with the Rest-Assured tool.


Assertible is a popular API testing tool that comes with many useful features. It provides a robust defense layer against web issues. It can also monitor websites and APIs continuously. Testers can reduce the bugs with the help of automated tests of Assertible. A free version of Assertible only gives minimum features but pro-version helps them gain attractive testing features.

9.Katalon Studio  

Katalon Studio is a free testing tool. It’s available in pro-version that contain many features. Let’s see some healthy features of Katalon Studio. It provides key support to all the testers. It helps testers to get ease deployment, high-quality recording utility, object spying, and code-assist utility and robust debugger.


Postman is a robust API testing tool that enables automated API testing. Postman is an easy GUI for sending HTTP requests and getting responses. Postman tool is built upon a set of quality tools, which are easy to use while testing any applications, APIs and others.

Postman has many useful features so testers can enjoy the benefits.  It can send REST, GraphQL, SOAP requests quickly within Postman. It also provides automated testing and generates readable documents quickly.


Do you need API Testing Services? Our experts have wide-range of knowledge about it. Please here to understand API testing methods and tools.



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