10 API Testing Tools You Can’t Live Without In 2023

Looking for API testing tools to streamline your API testing processes and deliver high-quality applications with ease? Here is a rundown of the top 10 API testing tools available today: from open-source options to commercial solutions, along with an in-depth analysis of their features and benefits.

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Any defects that arise in production have a risk of reputation; the software product needs to be tested thoroughly before deploying to the production environment. There are different levels of testing, such as unit testing, integration/API Testing, end-to-end testing, etc. When organizations follow multi-level testing, the defects can be reduced.

This blog post discusses the best API testing tools available in the market. Before that, let’s understand API testing and why you should automate it.

What is API?

API is the Application Programming Interface. It acts as a middle layer between the User Interface and the Database. API communicates and exchanges data from one software system to another.

What is API Testing?

API testing is a software testing practice that tests API for functionality, performance, and security. It can be considered Integration testing. API testing helps to test the application logic. It consumes less time and is more effective compared to UI testing.

Advantages of API Testing

  • Short execution time: The API tests are always less time-consuming as API testing doesn’t care about the application.

  • Stable results: The API test results are less flaky and more accurate.

  • UI independent: API Testing can be done early in the software development life cycle before developing UI. It doesn’t need any UI.

  • Integration testing: The API testing acts as integration testing; the individual components can be integrated to perform the API testing.

  • Less maintenance: The API tests can be written in any language, as API testing happens through HTTP requests and response calls. Any language which supports HTTP requests can be used for API Testing. API testing needs significantly less maintenance as APIs are at the middle layer.

  • Faster release: The API tests are quick and easy, which helps to reduce the release cycle.

Types of API Testing

The API testing can be performed with different intentions and broadly classified as below:

  • Functional Testing: The API functional testing checks the API functionality at the code level. The specific requirements are validated.

  • Security Testing: The API can be used for security testing. Any publicly exposed API needs to be validated against the security requirement. Security testing concentrates on authentication, injections, encryption techniques, etc.

  • Load Testing: The same API endpoints can be used in multiple places in the applications. The API should be capable of handling multiple requests parallelly. The Load testing involves testing the specific amount of users accessing the API endpoints by using the user simulation technique.

Why should you automate API Testing??

API Testing can be done either manually or using automation. The manual testing technique maintains the set of test cases in the repository. The QA team or developer needs to manually verify API test cases, such as status codes, API contracts, etc., by sending HTTP requests. Like any other manual testing approach, manual API testing is time-consuming, and it delays the release cycle.

Many API tools provide features to automate API testing. Some tools can be integrated into CI/CD pipeline to automate the release cycle. The API automation provides the results quickly and eliminates the QA/Dev dependency, which in turn helps ship the code faster.

In this page, we discuss the TOP 10 best API testing tools.

Note: The tools are not ranked and sorted randomly.

Popular API Testing Tools to Use in 2023


"API testing is no longer a bottleneck in your development process with Testsigma because you can: Test a variety of scenarios by storing input data as test data types and using them as parameters in your API requests. This data-driven approach helps improve test coverage and ensures your APIs are thoroughly tested.

Save time by validating APIs in real-time.

With Testsigma, you can easily invoke, validate, and debug APIs, and build complex test assertions with just a few clicks. And with our automated API testing solution, you can run your tests anytime, anywhere.

Test how UI and business layers interact with APIs.

By storing API response objects and using them downstream in functional tests, you can ensure that your APIs integrate smoothly with your web and mobile applications.

Testsigma API Testing tool

Chain API tests for increased coverage.

Testsigma supports a wide range of API tests, including unit, integration, and contract tests, so you can extend test coverage across the UI and API layers.

Test APIs continuously across your release cycle.

Testsigma supports native integrations with Jenkins, Circle CI, and other API lifecycle tools, so you can set up tests to run automatically as part of your CI/CD pipeline."

Start automating your API tests with Testsigma today.

Sign-up here


Postman - API Testing tool

Postman is the most developer-friendly tool. It is a proprietary testing tool owned by Postman Inc. Used for both manual and automation of API Testing, Postman provides the User Interface for performing all the actions for API Testing.

Postman tool is available as free and paid plans. The free plan comes with some restrictions though.

Advantages of Postman API Testing Tool

  • User friendly: The Postman tool is the most user-friendly tool. One doesn’t have to go through pages of documentation to learn. The user-friendly interface is self-explanatory and easy to learn.

  • Automation support: The tool allows to write the automation script in JavaScript language and can be integrated into CI/CD pipelines.

  • Multiple environments: The Postman tool can be configured to multiple test environments using the environment feature. It allows you to set up the environment variables, base URLs, etc.

  • Data-driven testing: It also allows testing API using the data-driven testing approach.

  • Supports multiple platforms: The Postman tool is available for multiple operating systems such as Windows, MacOS, etc.

  • Reports: It provides the HTML and Junit reporters.

  • API Mocking: The tool provides an easy way to mock the API.

Limitations of Postman

  • Free version limitations: The free version can be used only for basic API testing such as validating API responses, status codes, contracts, etc.

  • Performance Testing: The tool cannot be used for performance testing as it doesn’t give any insights and required metrics to analyze the performance.

  • Code Reusability: Postman test scripts are difficult to reuse.

REST Assured

REST assured - API Testing tool

REST Assured is a popular tool in API Automation. It is an open-source Java library, which provides end-to-end API testing functionality. It can be easily integrated into any Java-based testing framework. Rest Assured is now sponsored by the Parkster.

Advantages of Rest Assured

  • Open source: REST Assured is an open-source library, and all the features are available for free.

  • Easy to validate: REST Assured tool makes it easy to validate Rest services in Java.

  • BDD syntax: It supports the Gherkin syntax that is Given, When, and Then, which makes it easy to understand for anyone.

  • Easy to Integrate into continuous testing: As the REST Assured is a Java library it’s easy to integrate into Continuous testing platforms.

  • Data driven testing: It supports data-driven testing.

Limitations of Rest Assured

  • Ease of use: REST Assured is preferred for API automation. However, it’s very difficult to use for Manual API Testing as the tool doesn’t provide any UI’s.

  • Performance testing: REST Assured cannot be used for performance testing directly; it is designed for API Testing.

  • Reporting: REST Assured the reporters are not available out of the box.

  • Java-based library: REST Assured is a Java-based library. So, if you are using a framework other than Java language, you cannot integrate it directly.

  • Technical expertise: Unlike other tools, REST Assured requires sound technical knowledge of Java to implement the framework.

Soap UI

Soap UI - API Testing tool

SoapUI is one of the leading Open-Source API Testing tools, maintained by the SmartBear community. SoapUI can be used for automated functions, regression tests, and performance tests.

Advantages of SoapUI

  • Easy to use: SoapUI provides an easy drag-and-drop feature. This doesn’t require advanced technical expertise.

  • Easy to Debug: SoapUI tests are easy to debug, providing a clean user interface and debugging mechanism.

  • Multiple environment support: SoapUI tests can be configured for multiple environments such as QA, staging, production, etc.

  • Allows scripting: Developers/Testers can develop advanced scripts based on their needs.

  • Security testing: SoapUI can be used for Security Testing, as it supports vulnerability scanning techniques.

  • Performance testing: Unlike other API testing Tools, the SoapUI can be used for Performance Testing and Load testing, which helps in end-to-end performance monitoring.SoapUI can be used for Security Testing, as it supports vulnerability scanning techniques.

Limitations of SoapUI

  • Consumes memory: SoapUI consumes significant memory at a time, making it challenging to write the scripts.

  • Requires technical knowledge: Not every scenario works out of the box; you often need to write complex logic.

  • Limited to core features: The Ready API tool is built on top of SoapUI, which provides advanced features but requires a paid subscription.


Katalon - API Testing tool

Katalon is an all-in-one software testing tool. It is used for end-to-end testing, API Testing, Visual Testing, etc. It is a Free Proprietary tool by KMS technologies. Katalon also has paid version that provide extended features and support.

Advantages of Katalon

  • Easy to use: Katalon comes with a good user interface that is easy to use and understand.

  • BDD support: It supports BDD syntax, which makes it easy to understand the test scripts.

  • Data driven testing: Easy to adopt the data-driven testing model.

  • Hybrid testing: It supports both end-to-end testing and API testing. You can configure a hybrid framework, where a single framework can be used for multiple types of testing.

  • CI/CD Pipelines: Scripts can be integrated with CI/CD pipeline.

Limitations of Katalon

  • Restrictions of the free version: Katalon is a Proprietary tool, and many features are limited in the free version.

  • Community support: It has a smaller user base, so there is less community support. It’s difficult to get a workaround for complicated scenarios.

  • Scripting language support: The tool lacks Scripting language support.


JMeter - API Testing tool

JMeter is an open-source project. It is popular for Performance testing but can be used for API testing without hassle. It comes with its own UI, making it easy to write complicated tests.

Advantages of JMeter

  • Easy to set up: JMeter is easy to set up. You just need to download the JMeter jar and start testing.

  • Open source: As it is Open source, all the features are available for free.

  • Powerful CLI tool: Tests can also be executed using the JMeter CLI; it provides a lot of options to users, including reports.

  • Extensible: There are a lot of plugins available for the tool; you just have to download and use them.

  • Multiple operating systems support: As JMeter is a Java (jar) application, it supports all the operating systems which support Java.

Limitations of JMeter

  • UI glitches: JMeter UI is not smooth. Many users find difficulty while executing test scripts

  • Memory consumption: JMeter consumes high memory compared to other API automation tools, so glitches are common.

  • Complexity: JMeter scripting for API testing is complicated compared to other API testing tools.


Insomnia - API Testing tool

Insomnia is a Free tool managed by Kong. Used for API testing, it shares a lot of similarities with Postman.

Advantages of Insomnia

  • Setup: Just like Postman, Insomnia comes with an installer. You can download and install the installer and start testing.

  • Easy to learn: Like Postman, Insomnia is also easy to learn; many features are self-explanatory.

  • Testing support: Insomnia supports both manual and automation API testing where you can add the assertions to pass or fail the test cases.

  • Plugin support: Insomnia supports creating new custom plugins that can extend your testing framework.

  • Code snippet generation: Insomnia can generate the code snipped from the API schemas.

  • API Responses: Insomnia responses are not just JSON or XML; it allows you to view images, PDF documents, etc.

  • Inso CLI: The command line tool, helps to run the Insomnia test without any UI.

Limitations of Insomnia

  • Free version limitation: Insomnia also comes with paid support, which provides a lot of advanced features, however for the free version features are limited.

  • Lack of community support: The Insomnia tool is still gaining users so the community support is less compared to other API testing tools.

  • Documentation: Insomnia documentation is very difficult to understand for beginners.

  • Data-driven testing: Setting up the data-driven testing framework needs sound technical knowledge.


Karate - API Testing tool

Karate is an open-source API Testing tool. Though Karate is a BDD tool, unlike other BDD tools you don’t have to write the step definitions, as it has all the common scenarios ready for you. This feature makes Karate unique and easy to use.

Advantages of Karate

  • Less Coding Knowledge: Karate doesn’t need coding knowledge to start API testing. As it has step definitions ready, you can call those by defining your scenarios.

  • JSON validation: Karate JSON validation feature is shipped out of the box.

  • Language support: Karate supports both Java and JavaScript; one can do coding in either language.

  • Parallel execution: Karate supports parallel execution, so the test can be executed faster by using multithreading.

  • Logs and reporting: Karate provides detailed logs and reporting.

  • Performance testing integration: Karate can be used for performance testing.

Limitations of Karate

  • Documentation: The Karate documentation is complicated to understand

  • Debugging: Karate tests are difficult to debug.

  • Community support: Community support is moderate for Karate. One might find it difficult to get the solution for edge case scenarios.

  • Manual testing: Karate doesn’t provide any UI for manual testers. So, using Karate for Manual testing is not easy.


Cypress - API Testing tool

The Cypress is an open-source test automation tool. It supports different types of testing using JavaScript, such as Component testing, API Testing, End to end testing, etc. An all-in-one tool, Cypress can be used for API test automation, which helps to have different tests in a single framework.

Advantages of Cypress

  • Setup: Cypress is easy to set up. It is shipped as a node package; you can install just like any other NodeJS-based tool.

  • Out-of-the-box API testing support: Initially, Cypress was designed with end-to-end testing in mind, but today Cypress supports API testing out of the box. No external libraries are required.

  • Mocking Feature: Cypress provides the most efficient mocking feature that helps test the API even before they are ready.

  • Hybrid framework: Single framework can be used for Component, End to end testing, and API testing. No need to switch between the tools.

  • Less maintenance: Since all your tests are in a single framework, it reduces maintenance.

  • Community support: As Cypress is used by many organizations, there is good community support.

Limitations of Cypress

  • Limited API testing support: Extensive API testing might require using the extensions. The in-built API testing supports only basic scenarios.

  • Technical knowledge: Cypress is just not for manual testers; using API testing requires a good understanding of JavaScript.

  • Data driven testing: Though Cypress supports API Data driven testing, one should have the sound technical knowledge to set up the data-driven framework.

  • Reporting: Cypress doesn’t provide HTML reporters out of the box; one needs to rely on third-party plugins for HTML reports.

  • Performance testing: Cypress cannot be used for Performance testing.


Playwright - API Testing tool

The Playwright is Open-Source Automation Framework maintained by Microsoft. Like Cypress, Playwright is an End-to-end test automation tool, but it also supports API testing. Playwright helps to have a single framework for all different types of testing.

Advantages of Playwright

  • Easy to set up: Playwright is easy to set up and doesn’t require much time.

  • Programming languages support: Playwright supports multiple programming languages such as Java, JavaScript, Python, etc.

  • Mocks: Playwright supports mocking the API request, which helps to write the test before developing the API.

  • Documentation: It provides clear and understandable documentation with an example, which makes it easy to start the API testing.

  • Less maintenance: You can have multiple types of tests in your single framework, which reduces the maintenance of the framework.

  • Reporters: Playwright provides many different types of reporters, including HTML reporters, all are shipped out of the box.

Limitations of Playwright

  • No GUI: Playwright doesn’t provide any GUI like Postman or JMeter, so manual testers may find it difficult to use it.

  • Technical knowledge: One needs to have strong technical knowledge to set up the Playwright framework.

  • Performance testing: The framework cannot be used for API Performance testing.

  • Community support: Playwright is new to the market; community support is less compared to other API testing tools.

API Testing is critical as it provides more stable and accurate results than end-to-end testing. The major problem with the API testing tool is configuration, setup, and reporting. Most API testing tools require sound technical knowledge to build a robust API testing framework. Codeless automation is the next generation in the automation space, where anyone can automate tests, with no coding skills. Testsigma doesn’t require any installation, so if you have a Testsigma account, you can create, execute and maintain the tests from anywhere online. Sign up for free today!

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Frequently asked questions
Testsigma is one of the best tools for API testing in the market today. It provides a user-friendly interface, requires no coding skills, and supports the testing of RESTful and SOAP APIs. Testsigma also allows for cross-browser testing, mobile testing, and end-to-end testing, making it a comprehensive solution for testing applications. Other popular API testing tools include Postman, SoapUI, REST-assured, and Assertible.
There are several API tools examples that are used for testing APIs. Popular API testing tools include Testsigma, Postman, SoapUI, REST-assured, Assertible, JMeter, Karate DSL, and Apache JMeter. With Testsigma, you can also parameterize API testing and add API testing to a larger, end-to-end test script for your web and mobile apps.