21 Top API Testing Tools You Need To Know

Do you want to know more about API Testing Tools? You're in the right place.

API testing tools might have an impact on the quality assurance process even if you are an experienced QA Specialist.  As you know, API Testing is considered as crucial for automating or integration testing especially with Agile software development.

API Testing Tools will help you with unit testing, functional testing, load testing, security testing, Web UI testing, or penetration testing. To test an API you will need to use a testing tool to drive API.

We would like to propose a set of most popular API testing tools which you need to know if you want to make your tasks more efficient.

API Testing Tools List

  • API Fortress
  • Apigee
  • Assertbile
  • TestMace
  • Fiddler
  • HttpMaster
  • JMeter
  • Katalon
  • Postman
  • Rapid API
  • Rapise
  • ReadyAPI
  • Rest Assured
  • Runscope
  • Soap Sonar
  • SOAtest
  • Swagger
  • TestingWhiz
  • Tricentis Tosca
  • vRest

API Testing Tools details

API Fortress
API Fortress

API Fortress is a continuous testing platform for APIs. It is the final piece to complete your continuous integration vision. One platform to test functionality, performance, and load.

With API Fortress save time with automated test generation, benefit from true cross team collaboration, leverage your existing version control system, and seamlessly integrate with any CI/CD platform


Apigee is a full lifecycle API management platform that helps businesses accelerate with APIs. Apigee gives enterprises control over and visibility into the APIs that connect applications and data, across the enterprise and across clouds.

Google acquired Apigee in November 2016.



Assertible is used to test and monitor production web services, create scheduled assertions, and gain confidence in crucial infrastructure.

Assertible provides a reliable first line of defense against web service failures by providing simple and powerful assertions to test and monitor your APIs and websites. Lower the number of false positives in your automated QA tests and be confident your APIs are healthy.


TestMace is an IDE for working with APIs. The product is currently in beta testing, but the current version is stable and has a number of important advantages that can be useful for QA professionals and developers.

Some of which are: creating API testing scripts and scenarios of any complexity, Syntax highlighting, autocompletion, custom and embedded variables (e.g env), undo / redo, swagger API Import, Postman project import, Javascript code in tests.


Telerik Fiddler is part of a family of developer productivity tools for .NET and JavaScript ninjas from simple Fiddler Script to extensions which can be deveped using .NET language.

Fiddler is known as a proxy debugger, and its ability to capture traffic from nearly any source means the fastest way to generate API tests is to simply capture the API traffic from an existing client and modify and augment those tests as desired.

The new APITest extension to Fiddler greatly enhances its power to validate the behavior of web APIs.



HttpMaster is a web development and test tool to automate testing of web sites and services, including RESTful web services and API applications, and monitor their responses.

With HttpMaster you can easily execute and monitor requests to simulate client activity; it can execute requests against various web servers and display complete request and response data.

HttpMaster is also able to generate high volume of web traffic for improved testing and comes in two editions; free Express edition and commercial Professional edition.



Apache JMeter is open-source software that is popular for performance testing and is designed to load test functional behavior and measure performance. Apache JMeter may be used to test performance both on static and dynamic resources, Web dynamic applications.

It can be used to simulate a heavy load on a server, group of servers, network or object to test its strength or to analyze overall performance under different load types.

JMeter can read your testdata from the CSV file out of the box. API can be tested with multiple sets of data easily.

JMeter has a ‘Response Extractor‘ s  – which can be used to extract information from the API response (JSON / XML / Regular expression) and use it in the subsequent requests in the test.

You can easily integrate JMeter with Jenkins to run the test periodically and Jenkins has a plugin for JMeter to parse the result file & display nice charts.


Katalon Studio uses Apache Groovy, a scripting language for the Java platform. Groovy is a powerful dynamic language, which is ideal for creating test scripts. For test execution, Java libraries and Java compatible languages like JRuby and Jython are supported.

It has been a successful solution for many automation projects ranging from small to large teams for enterprise clients. Katalon Studio is free to use.

Katalon Studio supports the built-in integration with qTest, a powerful and easy-to-use test management system.

Katalon Studio is a test automation solution that leverages Selenium’s core engine. Although it uses several Selenium functionalities, it is not simply a Selenium wrapper.


Postman, a complete API development environment. With this app, developers are able to send requests, save responses, add tests, and create workflows.

Frequently, testers are required to perform an API testing and with an app like Postman this process becomes easy and it features a powerful and simple GUI, giving the ability to save the history of tested API requests, making reporting much easier.

Rapid API

RapidAPI is the world’s largest API marketplace where over half a million developers find and connect to thousands of public APIs.

RapidAPI processes 400 billion API calls each month. Its directory includes APIs from Microsoft, Stripe, SendGrid, Slack, Foursquare, Eventbrite, Yelp, Google Translate, Spotify, NASA, ProductHunt and more.


Rapise is a powerful and flexible software test automation platform that leverages the power of open architecture to provide the most rapid and flexible functional testing tool on the market today.

Rapise helps you test it all: web, mobile, desktop, & APIs. Rapise records tests, then lets you edit them in its easy-to-use spreadsheet-based editor. Or you can dig into their JavaScript-based engine that’s a breeze to extend.

Ready API

ReadyAPI allows you to build complex end-to-end functional, security, and performance tests with both the ease of an intuitive interface and the flexibility of an IDE.

ReadyAPI not only has an insightful dashboard built-in for quick up-to-date testing metrics, but also outputs JUnit, HTML, CSV, or other customizable reporting formats.

rest assured

REST-assured is a Java library that provides a domain-specific language (DSL) for writing powerful, maintainable tests for RESTful APIs.

REST-assured was designed to simplify the testing and validation of REST APIs and is highly influenced by testing techniques used in dynamic languages such as Ruby and Groovy.


The next API testing tool is Runscope.
A Runscope API test is a group of one or more HTTP requests executed sequentially to evaluate the uptime, performance, and correctness of an API. For each step in the test, you can define Assertions to validate response data and Variables to extract data to be used in subsequent requests.

SOAP Sonar

SOAPSonar provides automated testing of each API independent of client, device, or intended Consumer. Automatically generating a UI to provide immediate feedback to developers, testers, integrators, and security professionals.

Fully automated, SOAPSonar requires no scripting or script maintenance, reducing the time and skill level needed.

Regression testing can be automated, providing early identification of changes to the API or versions. Support for message and protocol layer identity standards allows for cloud testing.


SoapUI is the world's leading Functional Testing tool for SOAP and REST testing.

With its easy-to-use graphical interface and enterprise-class features, SoapUI allows you to easily and rapidly create and execute automated functional, regression, and load tests.

In a single test environment, SoapUI provides complete test coverage - from SOAP and REST-based Web services to JMS enterprise messaging layers, databases, Rich Internet Applications, and much more. And that's just the beginning.


Parasoft SOAtest brings artificial intelligence and machine learning to functional testing, to help users test applications with multiple interfaces simplifying automated end-to-end testing.

Parasoft SOAtest mitigates the cost of re-work by proactively adjusting your library of tests as services change.

Parasoft SOAtest efficiently transforms your functional testing artifacts into security and performance tests, to increase re-usability and save time


We couldn't forget about Swagger on our API testing tools list.

Swagger is a powerful yet easy-to-use suite of API developer tools for teams and individuals, enabling development across the entire API lifecycle, from design and documentation, to test and deployment.

Swagger consists of a mix of open-source, free and commercially available tools that allow anyone, from technical engineers to street smart product managers to build amazing APIs that everyone loves.


TestingWhiz is Codeless Automation Testing Tool which is providing automated testing solutions to global enterprises and software companies for their Software, Web, Mobile, Database, Cloud, Web Services and API testing.

TestingWhiz will be going to Automate, Execute, and Manage Test Cases Effortlessly & Efficiently. It also allows users to verify the critical functioning of their web applications and deliver efficient and effective web interfaces.

Tricentis Tosca

Tricentis Tosca
Tricentis Tosca allows testers to rapidly create API tests and integrate them into end-to-end test scenarios. Even if you’re new to API testing, it’s simple to get started in minutes. Just generate tests from service definitions or let the API recorder generate tests as you interact with the front end or run UI tests.



vREST is an automated REST API Testing tool which provides functions to validate your REST APIs. This is the core function of vREST.

Writing API test cases will ensure you to avoid any bugs after handing over the application to the client. You will be more confident in the build quality of your web application.

On the graph, you will see some of the API testing tools (features vs. costs).

api testing tools




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Grzegorz Kłos
Grzegorz Kłos - Apphawks Co-founder
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