Top 21 API Automation Testing Tools that Make Automation Easy

api automation testing

API testing is a sort of software testing that looks to see if APIs are up to par. API testing automation tools are becoming increasingly important for developers and programmers as APIs become an integral part of software development.

APIs do not have a visual user interface, so this testing cannot be done on the front end. 

In this article, we have reviewed the 21 best API automation testing tools and outlined their benefits and drawbacks in detail so you can make a wise and informed decision by the end of this article.

But, before jumping on the list of best tools, let’s first talk about what are API automation testing tools.

What is API Automation Testing Tool?

desktop illustration showing API automation testing tools

API testing, also understood as application programming interface testing is a type of software testing that assesses the quality of developed APIs and determines if they meet functionality, performance, and security requirements.

In recent years, there has been an expansion in interest in API/Web services testing. According to Smartbear’s 2017 research, the number of API testers who automate more than half of their tests is expected to increase by 30%.

Having the right tools and solutions for API automation tests and an efficient strategy is becoming increasingly important; API testing is critical for a successful CI/DevOps practice.

The top API testing tools are discussed in the following article, which range from open-source to commercial solutions, depending on the demands of testing teams.

5 Things You should consider before selecting an API Testing Tool:

API testing is unquestionably important for detecting faults across several application layers and providing a consistent customer experience. 

However, there are other ways and technologies on the market. For example, how can you get the return on investment you need to achieve the automation required to provide high-quality software at the speed needed by Agile and DevOps initiatives?

As our clients seek to address significant concerns such as omnichannel testing, test maintainability, Microservices, difficulty replicating failures, and rapidly changing APIs, we frequently receive questions like these. 

With today’s rapid development and releases becoming an increasingly crucial aspect of the business, finding the proper functional API testing solution to help your company flourish is more important than ever.

So, what exactly does this imply? When considering functional test automation solutions, there are five essential elements that you should check off.

#01 Core Capabilities and Ease of Use

Your API testing tools should be simple to use, which means that even a beginner user can pick it up and start using it with little training and achieve fantastic results. 

To that aim, the solution should be user-friendly and visually appealing while providing sufficient functionality to carry out complex tasks without scripts.

The following are some of the crucial capabilities:

  • Script-free and visual functionality
  • A framework for custom extensibility
  • Assertions and validations that are automated
  • Data-driven testing is a type of testing that is based on data
  • Check for reusability
  • Ability to quickly create tests before the launch of a service
  • Authentification

#02 Workflows that are more efficient

The ability to optimize your workflows is one of the most critical features your API testing tool should have. These should contain sophisticated methods that make test generation, message flow, data manipulation, and integrating your API testing solution into your existing requirements process easier.

The following are some of the workflows that your API testing tool should include to make your life easier:

  • Logic flow testing
  • AI-assisted test creation
  • Management and production of test data
  • Observation of events
  • Support for BDD (Cucumber)

#03 Technologies that are supported

Naturally, no tool can help you unless it supports all required formats and industry-specific message protocols. 

When you consider the modernization occurring across all industries, you must ensure that your tool is capable of supporting technology from the past, present, and future. These are excellent places to begin:

  • Testing of REST APIs
  • SOAP API evaluation
  • Testing with MQ / JMS
  • Microservices and IoT testing
  • Testing of databases
  • Testing on the internet
  • Performance evaluation
  • Mainframe, fixed-length, EDI, FIX, and other non-standard communication formats are also supported.

#04 Automation

Your API testing solution must provide a means for automating your tests. Using automation to run tests allows you to run your library of test cases as part of your nightly process or on-demand as needed. 

Your API testing solution should include both a command-line interface and APIs so that you can run your test cases programmatically as part of your continuous integration / continuous delivery process.

The following are the essential integrations and capabilities:

  • Integration of CI
  • Create system plugins
  • Execution from the command line
  • DevOps integration with open APIs

#05 Maintenance and Management

The continuing management and maintenance of an extensive library of test cases might be a burden once you’ve built a massive library of test cases. 

Your API testing solution should have techniques for determining which API tests are available to you, as well as the requirements that those API tests are linked to.

You should be able to organize your test case library into a meaningful configuration to support new application validation in numerous settings and obtain thorough test results reports that can be shared across multiple stakeholders. 

Finally, your API testing solution should include a change management feature that allows you to version different API test projects and understand the impact of application changes on these API testing projects.

Your API testing solution will have a cheaper total cost of ownership if it has long-term management and maintenance features like those stated below:

  • Integration with systems for managing requirements
  • Reporting is divided into two categories: basic and advanced
  • orchestration of tests
  • A method for dealing with change
  • On-premises and browser-based access are also available

List of 21 Best API Automation Testing Tools [with Pros & Cons]

#01 Postman

Postman is the following API testing tool after REST-assured. Postman is available in both a browser and desktop version, and it may be used to test API services. In addition, it permits the user to share their knowledge with the rest of the team effortlessly.


  • In comparison to other tools, this one is simple to use.
  • Parameters on method calls are simple to put up.
  • Commands can be stored.
  • It also has API development possibilities.


  • Enterprise pricing is quite costly.
  • The Enterprise edition is simple to set up and use, but it limits the number of requests it can handle.
  • It is not feasible to test multiple APIs at the same time.

#02 SoapUI

Another on-premises API testing tool is SoapUI, which allows developers to test REST, SOAP, GraphQL, and Web Services. 

SoapUI Pro is a sophisticated tool for creating, running and analyzing complicated tests on web services for development and testing teams. SoapUI has several unique features, such as test reports and SOAP API testing.


  • Groovy can be used to generate bespoke codes.
  • Without the need for manual intervention, data can be sent from one response to many API queries.
  • It saves your work so that you can come back to it later.


  • Web UI testing and mobile app testing are ineffective.
  • There is no documentation for this tool.
  • For newcomers, saving projects can be a little perplexing.

#03 Apigee

Apigee is another good API testing tool. Apigee, a Google Cloud service, has API administration capabilities. Apigee customers can use other editors like Swagger to support and build APIs and measure and evaluate API performance. 

Apigee was created with digital business in mind and the data-rich mobile-driven APIs and apps that drive it.


  • It tracks API traffic, error rates, and response times to identify performance concerns.
  • It is compatible with Node.js.
  • Controlling it is simple.
  • It’s a multi-step process that JavaScript powers.


  • It is forbidden to use JSON.stringify on Apigee objects (tokens).
  • Only one user can be active in a proxy at any given time.
  • Users can add target servers through the UI, but they must use the API to enable SSL.

#04 Karate DSL

Karate DSL, which is based on the Cucumber toolkit, makes it easy to design scenarios for API-based BDD tests without writing any code. 

It’s a unified framework that incorporates API test automation, mocks, and performance testing. It lets testers use a domain-specific language to write meaningful tests for online services.


  • The Karate DSL supports Multi-thread parallel execution.
  • It allows you to change configurations.
  • Karate DSL is a fantastic choice for GraphQL testing.
  • It works with both XML and JSON.


  • Auth schemes aren’t included by default in the tool.
  • There is no such thing as ‘Find Usage’ or auto renaming.
  • Supporting code becomes both time-consuming and costly.

#05 REST-assured

REST-assured is regarded as one of the most effective tools for testing Java APIs. Rest-assured is a Java Domain-Specific Language-based open-source platform. The Rest-assured API was built to test web APIs so that you don’t need to be an expert in HTTP.


  • You don’t need to be an HTTP specialist to perform this.
  • It has certain built-in functions, so you don’t have to code everything from scratch.
  • It supports the Given/When/Then syntax of behavior-driven development (BDD) testing.


  • Only the Java programming language is supported and does not expressly support SOAP APIs.

Also Read: Scriptless Test Automation- A Beginner’s Guide

#06 JMeter

Another open-source application load and performance testing tool is Apache Jmeter. It’s a popular tool for testing functional APIs. It includes a number of API testing capabilities and a number of features to make the process more efficient.


  • JMeter can be operated to test the performance of static and dynamic resources.
  • It gives developers the ability to replay test findings.
  • JMeter has a user-friendly interface that may be utilized in a command-line interface.
  • JMeter supports Per-thread cookies.


  • It necessitates the use of experienced testers.
  • It doesn’t support Javascript and, as a result, doesn’t accept AJAX requests by default.
  • In GUI mode, memory consumption is significant, resulting in many users receiving problems.

#07 API Fortress

API Fortress is perhaps the most potent REST and SOAP API testing and monitoring solution available. It fulfills a wide range of needs and proves to be an effective API testing tool. Complete API testing, including regression testing, is possible using API Fortress. 

It includes SLA monitoring, alerts, notifications, and reporting, just like the other solutions on the list.


  • It makes automated tests possible as part of a continuous integration process.
  • Data and notification integrations that are robust.
  • API monitoring and load testing should be done regularly.
  • Automate with a single click. Monitor functional uptime and test during development and deployments (CI/CD).


  • There are no free price tiers.
  • There are a few solutions for writing API testing with code.

#08 Citrus

Citrus is a testing tool that uses messaging protocols and data formats to automate testing. Citrus supports HTTP, REST, JMS, and SOAP testing. 

It can aid in the automation of integration testing for almost any messaging protocol or data format. It has strong validation features for XML message contents and allows complicated testing logic to be built.


  • Citrus consistently aids you in achieving your quality, function, and stability objectives.
  • It comes with a lot of documentation.
  • A smooth transition from development to production

#09 Dredd

Dredd is a command-line tool that allows you to test APIs and their documentation. It will enable you to perform ad-hoc tests using the API documentation’s name and the API’s URL—Dredd analyses the API documentation and checks all of the answers against the documentation’s specifications. 

As a result, it verifies the documentation’s accuracy and puts the API to the test. For example, PHP, Node.js, Python, Rust, Ruby, Perl, and Go are supported.


  • It’s simple to use and supports a variety of programming languages.
  • It verifies both APIs and API documentation.
  • Hooks are also supported.

#10 RapidAPI

RapidAPI is the first tool on our top API testing tools list. RapidAPI is the world’s largest API marketplace, with over a million developers using a single account to search, test, and connect to thousands of APIs. 

You can use RapidAPI for teams with external and internal APIs to collaborate on APIs. RapidAPI Testing can also be used on internal APIs by developers utilizing RapidAPI Teams or RapidAPI Hub.


  • It is entirely free to use.
  • You can test as numerous APIs as you want on the marketplace.
  • 10,000 public APIs in a single workspace.

#11 Paw

Paw is a lovely API testing tool made just for Mac. Paw can help you compose HTTP queries, evaluate a server’s response, and even generate client code, whether you’re an API creator or a consumer.


  • It’s simple to use.
  • It has a fantastic user interface.
  • When compared to other API testing tools, it has a more consistent performance.
  • It also has multi-dimensional settings for the environment.


  • Paw is now only available for Mac users.
  • Pricing that is too high (one-time purchase).

#12 Katalon Studio

Katalon Studio is a free API testing mechanism for APIs, web applications, desktop apps, and mobile apps. It makes development more accessible by combining all frameworks and plugins into a single package. 

The Manual and Scripting modes are suited for both beginners and specialists.


  • Katalon supports SOAP and RESTful queries.
  • It can be used for exploratory and automated testing.
  • It allows for CI/CD integration.
  • It’s a complete set of tools and frameworks.


  • Troubleshooting problems is tricky.
  • Debugging code is difficult, as there are no compile-time error checks.
  • However, there is no provision for distributed testing.

#13 HttpMaster

HttpMaster is a REST web service and web API application development and testing tool. It’s a universal HTTP tool that may also be used to construct other types of web applications, such as HTML forms. 

It also offers a simple and intuitive user interface and a tiny and compact installation package, and it does not require sophisticated technical knowledge.


  • Request chaining allows you to use request items to include data from earlier requests in subsequent requests.
  • API app testing that is automated.
  • RESTful service testing that is automated.
  • Execution in several threads.


  • It only works with Windows.
  • There is no support for JSON formatting.

#14 PyRestTest

PyRestTest is a REST testing and API micro-benchmarking API testing tool written in Python. JSON config files are supported for testing. 

Python allows for further customization of the device. It returns an exit code in the event of a failure scenario, which can be translated into trackable logs. In a nutshell, it returns exit codes when a query fails.


  • PyRestTest is a simple-to-use tool.
  • It can accommodate a large number of add-ons.
  • There is no need for a code.
  • It has few dependencies, making it simple to deploy smoke tests and health checks on a server.


  • Generator synchronization difficulties, etc.
  • Process management and other issues.
  • It’s possible that CurlMulti doesn’t use networking, as well as CurlMulti, does.

#15 Unirest

Unirest is a package that makes it easier to make HTTP REST requests. It is regarded as one of the most popular API automation testing tools. It’s free to use and comes in a variety of languages. 

Unirest has its documentation page that lists all of the REST methods available. It includes everything you’ll need to get started consuming APIs on Rakuten RapidAPI and elsewhere.


  • Unirests is compatible with eight programming languages, including Node, Ruby, Java, Python, and Objective C.
  • Unirest can be used in conjunction with the XUNIT or BDD runner.
  • It also provides a reference page with documentation.


  • Matchers, Extractors, and Assertions have no built-in library.
  • The HTTP Client Library is a simple HTTP client library.

#16 ReadyAPI

Smartbear’s ReadyAPI is a popular API testing tool. ReadyAPI is more than just a web service launcher; it’s also a dashboard-based analysis tool useful for appeals that take a long time to process.

ReadyAPI combines API performance testing, API functional testing, API virtualization, and API security testing into a single tool.


  • It ensures that all web services are thoroughly checked for quality.
  • API testing can be integrated with the CI/CD pipeline.
  • Dependencies are removed.
  • Execution of functional tests and job queuing in parallel.


  • The user interface isn’t the best.
  • However, both performance and memory management must be enhanced.

#17 AccelQ

AccelQ is a flexible testing platform that automates functional and API tests. AccelQ is a continuous testing platform for API automation testing that is hosted in the cloud. 

It helps with API testing without the need to write any code. For comprehensive testing, it provides chain API tests.


  • Management of a changing environment.
  • It has a defect-tracking feature.
  • Connects business processes to APIs.
  • Aligned with open-source.


  • Expensive
  • The delivery and release schedules are likewise quite aggressive.

#18 RoboHydra Server

RoboHydra Server is a great API testing solution for those who don’t have access to a server but need to test something. 

It’s a browser-based client testing tool (i.e., software that makes HTTP requests). It can handle graphical user interfaces for mobile apps, public APIs, and Java-based systems.


  • RoboHydra can be used in a variety of ways.
  • It enables clients-under-test to be connected to it and tests to be executed.
  • Any HTTP, HTTPS, or WebSockets client can be used to perform tests.
  • It runs on Node and is written in JavaScript.

#19 WebInject

WebInject is another free and open-source tool for testing web applications and services. WebInject is a well-known API testing tool that generates fully automated functional, regression, and acceptance test suites.


  • Gathers and studies data in order to provide an automated report.
  • Perl-based applications can be installed on Microsoft Windows, GNU/Linux, BSD, Solaris, and Mac OS.
  • It can run on a mixture of platforms thanks to the PERL interpreter.

#20 Appium

Appium is designed to test mobile applications; however, that does not imply it is limited in its capabilities. Instead, it’s an open-source automated testing tool primarily designed for mobile apps. 

It supports the automation of iOS and Android native, hybrid, and mobile web applications. Appium has grown in popularity and stability, establishing itself as one of the most effective mobile automated testing tools.


  • It helps a variety of programming languages, including Java, Python, Ruby, C#, and others.
  • It makes it simple for former web test automation experts because it uses the WebDriver API.
  • The term “open source” refers to a system with excellent Appium strength.
  • During execution, it takes care of the connection between Appium’s server and Xcode’s tools.


  • When compared to tests developed using Appium with Espresso or XCTest, Appium is a little slow.
  • It’s difficult for a novice user to take on without the help of an experienced user.
  • The documentation can be perplexing.
  • A qualified automation tester is necessary to generate quality code for automating mobile test cases.

Also Read: Appium Testing Tutorial: A Beginner-Friendly Guide

#21 RedwoodHQ

RedwoodHQ is an open-source tool for testing SOAP/REST APIs and supports various languages, including Java/Groovy, Python, and C#. 

It uses a web-based interface that allows several testers to execute tests on an application. This performance testing tool may be too shallow for developers.


  • It enables the user to compare the outcomes of each run.
  • An open-source framework for test automation.
  • Connecting to open-source automation tools like Selenium, Appium, Silk4J, and others automates any user interface.


  • The system is still incomplete and not ready for production, aside from problems.
  • It’s free and open-source, but it’s also incredibly adaptable and high-level.


This post discussed the best API testing tools. These top testing services can help you test web API functionality and avoid problems.

Almost all of the API testing tools mentioned above function well and are excellent choices. However, it all comes down to personal preference. 

These were my top API tools, but yours may differ significantly. There is no one-size-fits-all key for everyone, and each organization’s needs are unique.

There are many other API testing options outside these. For example, is there a tool for testing APIs missing from this list? If you leave a comment below, we’ll think about adding it to our list!

Moreover, you can click here to create your free account and start your testing journey with TestGrid.