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Testing APIs is no walk in the park, but it can be greatly simplified with the use of API testing tools—essential for ensuring the quality of your APIs.

Developers use a combination of APIs to make most of the services we access on the web or cloud available. However, before the services are made available to users, they go through a process. This process, known as API testing, checks if the API can perform at an optimal range.

A fully functional API is paramount for developers when executing a project. While testing, they look out for its reliability, performance, functionality and security. The ability to assess the API from this standpoint helps them discover any bugs and patch them before the user accesses them.

Testing APIs is no walk in the park, but it can be greatly simplified with the use of API testing tools as they are essential for ensuring the quality of your APIs and backend applications’ code. That said, we’ve handpicked the top 11 API testing tools for 2023 in this exhaustive list so you can get started easily.

What is API Testing?

API testing is a procedure used by developers to evaluate APIs performance, reliability, security and functionality. From this process, developers will get results that’ll tell them if there are bugs and patches to be made on an API before their software goes live.

They perform this process through a simulation that involves sending queries or traffic that would reach the API when accessible to its users, whether genuine or not. They monitor the API to see how it will respond to this traffic. If the results are positive, the API is safe for integration. If not, they will need to fix it, depending on the complexity of the API, or opt for total forfeiture.

API testing is integral in the software development life cycle of an API. Its goal is to prevent lapses that originate from APIs which affect end users. It also aims to prevent attacks like data scraping that emanate from API vulnerabilities. API testing makes the job seamless and saves time for developers by using specific tools to integrate, verify and validate APIs in various scenarios.

What to Look for in an API Testing Tool?

Since API testing has become a prerequisite process in the software development life cycle, the availability of API tools has also grown in the global markets. While most API tools can do a decent job in assessing your APIs, only a few can efficiently evaluate all layers of your APIs.

Developers face problems identifying the tools with the best features and capabilities to match the complexity of testing their APIs. Nonetheless, there are a few indicators to look out for before choosing an API testing tool. These indicators include:

  • Compatibility with the continuous integration and deployment pipelines
  • Capacity to do random tests at the same time
  • Ability to navigate its interface with ease
  • Quick response time during operations
  • Availability of API documentation

The ideal API testing tools provide detailed reports on where an underlying issue might arise. Many vendors in the market claim to have all these qualities embedded in their testing tools. This piece explores the API testing tool global market to present you with the best 11 tools in 2023.

11 Best API Testing Tools For 2023


SoapUI tool is dedicated to testing REST, SOAP and graphQL APIs. It is a complete API testing tool that prioritizes convenience for developers and testers with a seamless graphical interface, which supports the execution of automated functional, regression and load tests. Its paid version, ReadyAPI, is mainly for end-to-end testing. It also supports integration into continuous delivery and integration pipelines.

SoapUI is a leading automated functional testing tool. It can validate and enhance the lifecycle of your services and application without requiring a single bit of code from you. All you need to do is to drag and drop the action, even for the most complex scenarios. SoapUI also supports simulations which helps you to understand the behavior of your application when accessible to users. It can simulate events and save the cost of building a new environment. With a text generator, the tool conducts various security scans on your application to ensure that it is not vulnerable to attacks like XML bombs, SQL injections, cross-site scripting, etc.

Moreso, it brings advanced load testing to the game which predicts how the application will respond when it takes plenty of requests. In addition, an end-to-end automation feature saves time and money by allowing you to conduct Functional/Load tests and MockServices from any task scheduler in the command line tool.

Test Studio

Test Studio from Progress Telerik offers a testing solution that is simple to use and maintain for users. It supports the seamless integration of RESTful APIs into any environment. With Test Studio, you can automate API testing from end to end without a code and be sure that it will validate your model’s integrity and reliability.

The API test as step feature in Test Studio allows users to use API calls within the functional UI tests. Testers will experience a fast testing turnaround time with a focus on the right priorities. It also offers dynamic API tests, which lets you set variables for chain requests, response value comparison, and coverage for instances that require working with dynamic data.


Postman is a leading tool for Linux, MacOS and Windows. You can create functional, integration and regression tests with its CLI or a GUI that is easy to navigate. Its runtime supports popular patterns and libraries that test and debug quickly

Its interface is for all levels of users. Although it gives a platform for experts to run a test with scripts, beginners can also produce good results while doing little on its interface. It supports automated testing, allowing users to monitor the API and perform different requests and debugging. Developers and testers can now retain and share their built collection, which saves the time of starting afresh for a new testing process.


ZAP is a good tool for testing API security vulnerabilities and works well when scanning APIs with JSON and XML formats. With ZAP, you can import open API add-ons, Soap add-ons and files containing URL add-ons while exploring the API. It also supports APIs that use GraphQL and regression testing through proxy.

OWASP ZAP is an API security testing tool that runs on the command line. It comes with a script that is easy to use and configured to automate scans based on the user’s desire.

REST Assured

Developers who understand Java programming language can use REST Assured to test resting services. Its syntax helps testers conveniently create requests without having to code from scratch.

Users do not need to understand HTTP to use this tool. However, the scope of REST assured is limited to only developers who understand Java. Java developers will only require an 8.0 version of software to enjoy the tool, which supports integration testing and contains enough validation mechanisms. REST assured is equally able to combine tests of REST services and UI in a single framework.

Apache JMeter

Apache JMeter is another tool that is mainly for users’ Java experience. It is a great API testing tool to conduct functional and performance tests for REST, SOAP services, etc. JMeter supports the simulation of high requests on your APIs to evaluate its ability and performance under various circumstances.

JMeter gives you a platform to conduct as many load and performance tests as possible, with endless capabilities on various services. It is compatible with OS such as macOS, Linux and Windows.

In addition, JMeter gives you an option of a CLI and GUI, which is simple enough to help you create and conduct your tests. It is also portable since it supports different plugins and integrations.

Rapid API

Rapid API supports deep functional testing and monitoring for REST, SOAP and GraphQL APIs. It also comes with improved efficiency, which allows you to easily integrate the tool into CI/CD pipelines, RapidAPI and RapidAPI Enterprise hub for easy collaboration among teams.

It has a comprehensive testing environment and a friendly interface for beginners and experts to create and conduct API calls and tests. With Rapid API, you will get a global monitoring feature that evaluates API tests through reports, analytics, etc. It also offers OAuth 2.0/OpenID Connect, header validation and injection flaw prevention for API security.

Karate DSL

Karate offers services that allow testers to create simulations to access your API performance. Its predefined steps are a reliever for beginners and a time saver for developers who want a fast testing experience.

Karate DSL is a Cucumber-JVM-based testing tool that supports API test automation, UI automation and performance in the same environment. Its debugging feature saves time and makes it seamless to fix issues on your API by replaying steps during the assessment. It also comes with other characteristics which make it easy to work with JSON and XML. They include an embedded JavaScript engine, switching configurations, support for data-driven tests, etc.


Swagger is an efficient tool for the API development life cycle. It does API testing for REST, SOAP and GraphQL as one aspect of software development, which ensures that the applications respond correctly to requests and are secure.

The Swagger inspector feature makes validations seamless by its capacity to inspect API requests and responses to make sure they are working adequately. Through its collaboration with the Rest API platform, you can create multiple scenarios to validate schema rules and inject various data into parameters. The rest API also helps to provide automated reports on endpoints.

Katalon Studio

Katalon can perform efficient tests on REST and SOAP 1.1/1.2 requests. You can also import tests from WSDL, Swagger and Postman API on this platform. It is a data-driven testing tool that supports BDD with Cucumber files and the Gherkin editor. With Katalon, you can reapply test collections and descriptions across different projects.

Aside from being easy to maintain, Katalon is scalable since it allows CI and DevOps practice through embedded integrations. Moreso, autocompletion, inspection, snippets, a debugger and a dual interface help Katalon improve scripting, debugging and maintenance.

Google Apigee

Apigee API is a reliable tool that can design, monitor, test and secure your API with robust policies. It is a multi-step JavaScript tool created to help users manage their API features flexibly. This tool tracks the traffic to reach the API, its response behavior and its error rate.

Apigee has one of the best features that detect security misconfiguration in an API and apply possible fixes. It is also a scalable tool that performs anywhere with maximum functionality expectations.

Comparing API Testing Tools

Make sure the API testing tool you choose meets your needs when it comes to compatibility with your existing CI/CD flow, asynchronous testing, usability and support, and performance.

Why to Choose Test Studio to Test Your APIs

Using simple-to-create and maintain API tests, Test Studio enables teams to increase their functional testing efforts regardless of testing seniority or expertise.

With Test Studio, you can:

  • Test APIs automatically on desktop and web without writing any code
  • Check the dependability and integrity of your web services without putting in extra work
  • Integrate Your RESTful API tests into any deployment environment

Want to see Test Studio in action or check whether it fits your test automation needs? Request a quick demo here.

Frequently Asked Questions (FAQs)

What Tool is Used for API Testing?

There are many great tools for API testing; however, the best must support integration, reusability, scalability and running asynchronous tests to save time. A good API testing tool also comes with an easy user interface.

Is API Testing in Demand?

APIs are integral in many services we access on the web or cloud; therefore, it is crucial to test them to evaluate their functionality, reliability, performance and security.

Does API Testing Need Coding?

Most great API testing tools do not require users to use coding; you can automate API testing just by following the manuals.

Is the API Test Easy?

Many API testing tools that support test automation have made it seamless. However, API testing experience can vary depending on the complexity of the API.

How Many Types of API Tests are There?

There are about nine types of API tests. They include functional, validation, UI, Load, penetration, runtime, security, fuzzing and compliance testing.

What is the Best Tool for API Testing?

Your needs will determine the best fit for your organization, but an API testing tool worth checking out is Test Studio.

About the Author

John Iwuozor

John Iwuozor is a freelance writer for cybersecurity and B2B SaaS brands. He has written for a host of top brands, the likes of ForbesAdvisor, Technologyadvice and Tripwire, among others. Hes an avid chess player and loves exploring new domains.


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