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10 Best API Testing Tools & Approaches to Know in 2023-2024

10 Best API Testing Tools & Approaches to Know in 2023-2024

Developers have more options when it comes to testing their APIs. They can use multiple testing tools and each API has their own unique set of features and advantages. This makes it difficult for developers to find a tool that meets their needs. This problem is only going to get worse as testing tools continue to improve and evolve.

There are so many testing tools available today that it can be difficult to know where to start for an api integration company. There is a wide range of options available, each with its own unique set of features and capabilities. As testing tools continue to improve and evolve, the landscape is only becoming more complicated. The good news is that no matter which direction you go, you’re bound to find a tool that suits your needs.

On the other hand, as an API developer, it can be difficult to determine which testing tool to use. There are so many different tools available, each with its own unique set of features and capabilities. This makes it difficult to determine which testing tool is best for your needs. This problem only gets worse as testing tools continue to improve and evolve.

Fret not, in this blog piece, we’ve compiled a list of the best API testing tools that will expedite your work. Let’s recap the basics of API testing before we check out the top 10 API testing tools in 2024.

What You Should Know About API?

API Testing Tools

An API is an Application Programming Interface, which is a piece of programming code that facilitates smooth communication (transmission of data) between two software applications. APIs are a key part of the software development lifecycle (SDL), allowing software applications to communicate with each other and other services, including Shipping API Integration. APIs are a key part of the software development lifecycle, allowing software applications to communicate with each other and other services. The most common use of APIs is to allow software applications to interact with other services such as databases or web services. When a user requests information from an API, it is driven to the service provider who will generate a result, and it will send back the result to the user. The best way to understand an API is to think of it as a set of instructions that allow two programs or applications to communicate with each other.

The other common use is within mobile app testing, wherein APIs is to allow two programs or applications to communicate with each other. When a user requests information from an API, it is directed to the service provider who will generate a result, and it will send back the result to the user.

Top Features of API

  • Serves as a middle man and facilitates the exchange of data between two different applications.
  • Helps in embedding content faster from any site or application.
  • Easy-to-customize the content and services they use most frequently.
  • Simple, flexible, and easy to use.
  • Offers incredible developer support.

Top 10 API Testing Tools


1. Postman

Postman is one of the most popular API testing tools in the world, used by developers, testers, and project managers alike. It is used for testing APIs and API-related services, sending and receiving HTTP requests, creating, and sending HTTP POST requests, and much more.

The Postman API enables you to send HTTP requests to web services and receive the responses in JSON format. It provides powerful testing and monitoring capabilities, and you can combine Postman API testing with Katalon Studio testing to create powerful API test suites.

Key Features

  • Allows Boolean tests without the need for a command line.
  • Can extract API data using Postman’s interface.
  • Has built-in tools to automate tests, debug, monitor API, run requests, and workspaces.
  • An easy-to-use REST client.

2. Katalon Studio


Katalon Studio is a free tool that can be used to automate tests for web development services and mobile app development. It can be used to test the functionality of a web service, the functionality of an application or the functionality of a mobile app. Using Katalon Studio, you can create tests that will drive requests to web services, manipulate the user interface of an application, or simulate the actions of a mobile app. You can then use the results of your tests to find bugs or validate the behaviour of your app or service.

Key Features

  • Supports the commands and parameterizes functions.
  • Offers the ability to integrate UI and API/Web services across various platforms, including Windows, Mac OS, and Linux.
  • Supports AssertJ, to build fluent assertions in a BDD style.
  • Good for automated and exploratory testing

3. Tricentis Tosca

Tricentis Tosca is a software testing tool that supports HTTP (Hypertext Transfer Protocol), AMQP (Advanced Message Queuing Protocol), SOAP (Simple Object Access Protocol), and many other protocols. It is more like a testing framework with an emphasis on reliable, accurate, and informative testing output.

Key Features

  • Enhances reuse and simplifies scrip maintenance.
  • Good for end-to-end testing by allowing API tests to be run across mobile, cross-browser, and packaged apps.
  • Ensures regression tests are completed quickly and efficiently.
  • Performs manual testing without Tosca environments.
  • Encourages sustainable automation.

4. Rest-Assured

Rest-assured is an open-source platform that offers Java domain-specific languages (DSLs) to make it easier to test REST services. It can be easily used as a starting point for a REST API as well as a means for testing endpoints before they are released.

Key Features

  • In-built functionalities, enable users to develop hassle-free
  • Offers several authentication methods to test and validate a secured API.
  • Supports all HTTP methods, and commands, such as POST, GET, PUT, DELETE, OPTIONS, and PATCH.
  • Good for seamless integration of the Serenity automation framework.

5. SoapUI

The next generation of functional testing, SoapUI is a powerful, easy-to-use test tool that enables you to test the functionality of your SOAP and REST APIs. SoapUI provides the most advanced and comprehensive API test framework available, built on years of experience helping developers and software companies test their APIs. The SoapUI test framework creates tests for your API using industry-standard protocols like SOAP and REST and lets you specify exactly which HTTP methods, headers, and response content to use. The tests are also dynamic, so they automatically adjust to the output of your API when the input changes.

Key Features

  • Simplifies complex tasks of working with JSON and XML and building rapid tests.
  • Enforce consumer interaction with APIs by loading data from Excel, files, and databases.
  • Enables access to the complete source code of SoapUI via the free package
  • Supports data-driven testing
  • SoapUI supports Data-driven testing

6. JMeter


The Apache JMeter open-source performance testing tool is a powerful platform for testing the performance of web applications, web services, and other applications and services. JMeter is best used for testing the performance of web applications, services, and other applications and services. It is also used for testing the performance of web pages, websites, and web apps. Apache JMeter is an open-source tool that enables you to test the performance of web applications, services, and other applications and services.

Key Features

  • Integrates JMeter with Jenkins, users can include API tests within CI pipelines.
  • Flexible for testers to customize it according to their requirements.
  • Used for both dynamic and static resources to test performance.
  • Performs load and performance tests for a wide variety of server types.

Must read: How to Make Use of JMeter tool for API Testing in Mobile App Development?

7. Assertible

The Assertible API offers reliable uptime and performance monitoring for any cloud or service provider. It is built to be highly performant, scalable, and reliable, so you can be confident with the uptime, quality of service, and performance of your API.

You can use the tool to monitor the status of your application instances, keep track of the performance of your application and increase your application’s availability by making sure that you’re always running at 100%.

Key Features

  • Easy to execute API tests
  • Seamless integrations with tools such as GitHub, Slack, Zapier, etc.
  • Supports validation of HTTP responses with turn-key assertions

8. Karate DSL

KARATE DSL is a unified framework for API automation testing, mocks, performance testing, and load testing. It was initially designed for testing microservices and API-driven applications.

Key Features

  • Allows tests to be written in every language dealing in HTTP, JSON, or XML.
  • Gives robust assertion capabilities.
  • Supports switching configuration for parallel multi-threading execution.
  • Testing and generating reports
  • Reuses payload data and user-defined functions across tests with this tool.

9. Swagger


Swagger is a web-based API testing tool that lets users begin testing functionality, security, and performance right from the open API specification for API Testing in Mobile App Development. It also provides a set of tools for API testing, open source test suites, and a complete checklist for API testing, so users can validate their API design and ensure their APIs meet the requirements of Swagger, API Blueprint, OpenAPI Specification, and other open standards.

Key Features

  • Allows inspection API response-requests a
  • Validates schema rules by importing users’ API definitions.
  • Generates assertions against endpoints and injects synthetic data into parameters automatically.
  • Supports all types of services including REST, SOAP, and GraphQL.


ACCELQ is a unique test automation offering that focuses on the design and maintenance aspects of the test automation life cycle. You’ll be pleasantly surprised by its intuitiveness and comprehensiveness when you try it. It’s a cloud-based continuous testing platform that provides a codeless approach to test automation. It provides test automation and test management capabilities for both API testing and functional testing tool.

Key Features

  • Automates API testing without requiring users to write a single line of code.
  • In order to guarantee reliable test execution, ACCELQ adapts intelligently to unexpected changes in the application.
  • Additionally, ACCELQ automatically generates test cases using AI (Artificial Intelligence).
  • Ensures a seamless integration between business processes and corresponding APIs.


Technology is leading every possible space around us, and in this, API testing is the winner. It not just automates testing, but also adds tools to meet development demands. If you want to hire QA testers, with immense experience and skill-set, then your search ends here at CMARIX.

We are here to help you to select the best available tools that fit your business needs and offer an incredible user experience. Get in touch with us and drop your requirements at, we are here to transform your business.

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Written by Atman Rathod

Atman Rathod is the Founding Director at CMARIX InfoTech, a leading web and mobile app development company with 17+ years of experience. Having travelled to 38+ countries globally and provided more than $40m USD of software services, he is actively working with Startups, SMEs and Corporations utilizing technology to provide business transformation.

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