10 API Testing Tools You Can′t Live Without

Looking for the best API testing tools to elevate your application quality? Discover the top 10 API options, from open-source to commercial, with detailed feature and benefit analysis. Dive in to streamline your testing process now!


What Is An API Testing Tool?

An API testing tool is a test automation platform or framework designed to automate API testing. Tools like Testsigma automate API testing by allowing you to send requests to an API, receive responses, and validate its functionality. These tools help developers detect and correct issues before they impact the end-user experience.

10 Top API Testing Tools To Use

From automation capabilities to comprehensive test reporting, these tools offer various features to meet your API testing needs. Here is a list of the most widely used API testing tools in the market:

1. Testsigma

Testsigma is a robust cloud-based, low-code AI-driven test automation tool that supports API testing. With Testsigma, API testing is no longer a bottleneck in your development process. You can test various 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.

Testsigma- QA automation tools

Key Benefits of Testsigma:

  • Simple and Easy-to-Use Interface: Navigate through Testsigma′s features easily, making it accessible to everyone on your team.

  • Versatile Testing Capabilities: From codeless to code-based testing, Testsigma is designed for both technical and non-technical users.

  • Unified Testing Platform: Not just for APIs, you can automate your UI testing for web, mobile, and desktop apps all in one place.

  • DevOps and CI/CD Integration: Testsigma fits perfectly within your existing DevOps and CI/CD pipeline to continuously test across your release pipeline

  • API Support: Test using REST API methods like GET, POST, PUT, DELETE, and HEAD.

  • Flexible Response Validation: Validate API responses with different comparison modes for thorough testing.

  • Low-Code Response Verification: Simplify API tests without extensive coding, especially for response verification.

  • Enhanced Object Storage: Easily manage and store objects directly through the UI, a feature not commonly found in other tools.

  • Post-Test Actions: Implement custom actions based on API test results, such as rolling back to previous configurations.


Experience Testsigma with our free trial and discover the flexibility of our plans, which are designed to fit the needs of teams of all sizes.

Who′s It For?

Whether you are a developer, QA professional, or part of a startup or large enterprise, Testsigma offers a comprehensive solution for automating end-to-end testing of web, mobile, and desktop apps. Its versatile testing types, including cross-browser, UI, integration, regression, visual, portability, and compatibility testing, make it ideal for any team aiming to enhance its testing efficiency and product quality.

REST Assured

Testsigma - Rest assured

REST Assured is a popular tool in the realm of API Automation. As an open-source Java library, it facilitates end-to-end testing functionality for APIs. This tool simplifies testing REST services within Java applications and has garnered support from Parkster, enhancing its development and reach.

Features of REST Assured:

  • Open Source: Being an open-source library, REST Assured offers its comprehensive features free of charge.

  • Easy Validation: It simplifies the validation of REST services in Java, making it accessible for testing professionals.

  • BDD Syntax Support: REST Assured supports Gherkin syntax (Given, When, Then), making tests easy to write and understand even for those less familiar with coding.

  • Integration with Continuous Testing: Its compatibility with Java makes integrating into continuous testing platforms straightforward, enhancing automation workflows.

  • Data-Driven Testing: REST Assured supports data-driven testing, allowing for more robust and comprehensive test scenarios.


REST Assured is an open-source tool that is available at no cost. This makes it an attractive option for individuals and organizations looking to enhance their API testing processes without incurring additional software expenses.

Who′s It For?

REST Assured is designed for developers and testers working with Java-based applications looking to automate their API testing processes. It requires a sound technical understanding of Java, making it most suited for those comfortable with the language. While it is an excellent tool for API automation, its lack of a user interface for manual API testing and direct performance testing capabilities means it might not be the best fit for all testing scenarios.

Soap UI

Testsigma - Rest assured

SoapUI is one of the leading Open-Source API Testing tools maintained by the SmartBear community. It is designed to simplify the process of testing APIs for functionality, reliability, performance, and security. The tool can be used for automated functions, regression, and performance tests, making it a versatile choice for developers and testers.


  • Easy to use: SoapUI provides an easy drag-and-drop feature, enabling users to create and execute tests quickly without advanced technical expertise.

  • Easy to Debug: Offers a clean user interface and debugging mechanism that simplifies identifying and fixing issues in tests.

  • Multiple environment support: Tests can be configured for different environments, such as QA, staging, and production, facilitating seamless testing across various stages of development.

  • Allows scripting: Users can develop advanced scripts to extend testing capabilities beyond assertions and validations.

  • Security testing: Supports vulnerability scanning techniques, allowing for comprehensive security testing.

  • Performance testing: Capable of performance and load testing, aiding in assessing end-to-end performance under various conditions.


SoapUI is free and open-source, offering core features necessary for API testing. For users requiring advanced functionalities, such as enhanced security testing, detailed reporting, and support, SoapUI provides a paid version known as ReadyAPI. Pricing for ReadyAPI depends on the specific needs and the scale of use, and interested users should contact SmartBear for a quote.

Who′s It For?

SoapUI is suitable for developers and testers of all skill levels. Beginners will appreciate its easy-to-use interface and drag-and-drop functionality, while experienced users can leverage its scripting capabilities to create complex test scenarios. It is ideal for organizations looking for a flexible and powerful tool for comprehensive API testing across various stages of software development, from individual developers working on small projects to large teams handling enterprise-level applications.


Testsigma - Rest assured

Katalon is an all-in-one software testing tool designed for various testing needs, including end-to-end testing, API Testing, Visual Testing, and more. Developed by KMS Technologies, Katalon offers a comprehensive solution for testing projects with both free and paid versions available. The paid version provides additional features and support for more advanced testing requirements.


  • Easy to use: Katalon boasts a user-friendly interface, making it accessible for users with different levels of expertise.

  • BDD Support: The tool supports Behavior-Driven Development (BDD) syntax, enhancing the clarity and understanding of test scripts.

  • Data-Driven Testing: Katalon simplifies the adoption of data-driven testing approaches, allowing for more flexible and comprehensive test scenarios.

  • Hybrid Testing: With Katalon, users can perform end-to-end and API testing within a single framework, supporting a hybrid testing strategy.

  • CI/CD Pipelines: It facilitates integration with Continuous Integration/Continuous Deployment pipelines, streamlining the testing process in DevOps practices.


Meanwhile, Katalon offers a paid version that unlocks extended features and provides support. The pricing for the paid version varies based on the package and subscription model chosen, catering to different scales of project needs.

Who′s It For?

Katalon suits many users, from individual developers and QA testers to large enterprises. Its ease of use and comprehensive feature set make it ideal for those looking to streamline their testing process, adopt hybrid testing methods, and integrate testing into their CI/CD pipelines. However, it′s essential to consider the limitations of the free version and the smaller user community, which may impact support and learning resources for more complex scenarios.


Testsigma - Rest assured

JMeter, an open-source project, is renowned for its performance testing capabilities, though it also effortlessly accommodates API testing. It features a user-friendly interface that simplifies the creation of complex tests.

Features of JMeter:

  • Easy to set up: Setting up JMeter is straightforward. It just requires downloading the JMeter jar to start testing.

  • Open-source: Being open source, JMeter offers all its features for free, making it an accessible tool for everyone.

  • Powerful CLI tool: Beyond its UI, JMeter can execute tests via its command-line interface, providing users extensive options, including reporting functionalities.

  • Extensible: The tool's capabilities can be expanded through numerous plugins, which users can easily download and integrate.

  • Multiple operating systems support: As a Java (jar) application, JMeter is compatible with any operating system that supports Java, broadening its usability.


JMeter is an open-source tool; hence, it is available for free. Users can leverage all of its features without cost, making it an economical choice for individuals and small organizations.

Who′s It For?

JMeter is suitable for developers and testers who require a robust performance and API testing tool. Its extensibility and support for multiple operating systems make it a versatile choice for many users. However, due to its complexity and high memory consumption, it might be more suited for those with more experience in testing or those willing to invest time in learning the tool.


Testsigma - Rest assured

Insomnia is a robust tool managed by Kong explicitly designed for API testing. It shares many similarities with Postman but also boasts unique features that make it an attractive option for developers and testers. Insomnia facilitates manual and automated API testing, allowing users to add assertions to pass or fail the test cases. It′s renowned for its user-friendly setup, requiring a simple installer download. Its intuitive interface and self-explanatory features make learning Insomnia a breeze for newcomers.

Key features of Insomnia include:

  • Easy Setup: Comes with an installer for straightforward download and installation.

  • User-Friendly: Features are easy to understand and use, making the learning curve gentle.

  • Testing Support: Offers comprehensive support for both manual and automated API testing.

  • Plugin Support: Users can create custom plugins to expand testing capabilities.

  • Code Snippet Generation: Automatically generates code snippets from API schemas.

  • Rich API Responses: Supports viewing responses in various formats, including JSON, XML, images, and PDF documents.

  • Inso CLI: A command-line tool that enables running tests without the UI.


While Insomnia offers a free version, it has paid support options that unlock advanced features. However, users of the free version may need some limitations regarding the features available. Insomnia has a smaller community than other API testing tools, which might affect the availability of third-party resources and support. Additionally, its documentation can be challenging for beginners, and setting up data-driven testing frameworks requires specific technical expertise.

Who′s It For?

Insomnia is ideal for developers and QA testers looking for a powerful yet straightforward tool for API testing. Its simplicity makes it suitable for beginners, while the advanced features in the paid version cater to the needs of more experienced users. Whether you′re working on manual testing or looking to automate your tests, Insomnia provides a flexible platform to suit various testing requirements.


Testsigma - Rest assured

Karate is an innovative open-source API Testing tool that stands out for its unique approach to Behavior-Driven Development (BDD). Karate does not require users to write step definitions, unlike traditional BDD tools. It comes with a comprehensive set of predefined scenarios, making it remarkably easy to start with API testing without a steep learning curve. This attribute simplifies the test development process and accelerates it, catering to both technical and non-technical users alike.

Features of Karate:

  • Ease of use: users can conduct API testing with minimal coding expertise. Users can define their scenarios without getting involved in complex coding.

  • JSON Validation: Karate comes with an out-of-the-box JSON validation feature, emphasizing its focus on modern web standards and technologies.

  • Language Support: Karate supports both Java and JavaScript, allowing users the flexibility to script their tests in either programming language according to their proficiency or project requirements.

  • Parallel Execution: Karate supports parallel execution and leverages multithreading, enabling a faster testing process and quicker feedback cycles.

  • Logs and Reporting: Karate provides detailed logs and comprehensive reporting, ensuring transparency and ease in tracking test execution and outcomes.

  • Performance Testing Integration: Karate can also be utilized for performance testing, demonstrating its versatility as a testing tool.


As an open-source tool, Karate is available at no cost. This makes it an accessible option for individuals, startups, and enterprises seeking an effective yet budget-friendly API testing solution.

Who′s It For?

Karate is designed for a wide range of users, from developers and QA engineers who seek an efficient way to write and manage API tests to non-technical stakeholders who need to understand or contribute to the testing process without deep coding knowledge. Its ease of use and powerful features make it suitable for small teams and large enterprises aiming to streamline their API testing practices.


Testsigma - Rest assured

Postman is a comprehensive tool designed specifically for API testing, making it an indispensable developer asset. It stands out as a proprietary tool owned by Postman Inc., tailored for manual and automation testing processes. This developer-friendly tool is celebrated for its intuitive User Interface (UI), enabling users to execute an array of actions pertinent to API testing quickly.


  • User Friendly: Postman's interface is notably intuitive, allowing users to quickly familiarize themselves without delving deep into documentation.

  • Automation Support: Users can automate tests by writing scripts in JavaScript, facilitating integration into CI/CD pipelines.

  • Multiple Environments: It supports configuration across various test environments, enhancing flexibility with environment variables and base URLs.

  • Data-driven Testing: Postman accommodates data-driven testing approaches, enabling thorough API evaluations.

  • Platform Compatibility: The tool is accessible on several operating systems, including Windows and MacOS, ensuring wide usability.

  • Reporting: It generates reports in HTML and Junit formats, offering clear insights into the testing process.


Postman offers both free and paid plans. The free version provides basic API testing capabilities with certain limitations. Users can opt for the paid plans for extended features and fewer restrictions, designed to cater to more comprehensive testing needs.

Who′s It For?

Postman is ideally suited for software developers and QA engineers who require a versatile tool for API testing. Whether for simple validation tests or intricate automation and integration tasks, Postman′s robust feature set and user-friendly design make it a top choice for professionals aiming to enhance their API testing workflows.


Testsigma - Rest assured

Cypress is an open-source test automation tool that significantly streamlines the testing process for developers and QA engineers. It specializes in using JavaScript for various types of testing, such as Component testing, API Testing, and End-to-end testing. Cypress distinguishes itself as an all-in-one tool capable of handling API test automation efficiently, enabling different tests to be conducted within a single framework.

Features of Cypress:

  • Ease of Setup: Cypress simplifies its integration into projects as it comes packaged as a Node package, making the installation process straightforward.

  • Out-of-the-box API Testing Support: Originally focused on end-to-end testing, Cypress now equally excels in API testing without additional libraries.

  • Mocking Feature: One of Cypress's standout features is its efficient mocking capabilities, allowing for the testing of APIs even before their completion.

  • Hybrid Framework: Cypress is a versatile tool that can be used for Component, End-to-end, and API testing without switching between different tools.

  • Low Maintenance: By centralizing tests within one framework, Cypress reduces the time and effort required for maintenance.

  • Community Support: With widespread adoption across numerous organizations, Cypress benefits from strong community support.


As an open-source tool, Cypress can be used without licensing fees, making it an accessible option for individuals and organizations. Users might consider Cypress′s paid plans for advanced features and support, which offer additional benefits such as access to the Cypress Dashboard for better test management and insights.

Who′s It For?

Cypress is designed for developers and QA engineers who are comfortable with JavaScript and seeking a robust, single-framework solution for their testing needs. It suits teams looking for a tool that supports front-end and API testing, streamlining their workflow. While Cypress is user-friendly and requires minimal setup, a good understanding of JavaScript and test automation principles is recommended to maximize its capabilities. It′s particularly beneficial for teams prioritizing fast, reliable test automation and those who wish to avoid the maintenance overhead associated with multiple testing tools.


Testsigma - Rest assured

Playwright is an open-source automation framework maintained by Microsoft that functions as an end-to-end test automation tool that uniquely supports API testing. This tool enables the use of a single framework for various types of testing, streamlining the testing process across different testing requirements.

Features of Playwright:

  • Easy Setup: Setting up Playwright is straightforward, requiring minimal time and effort.

  • Programming Languages Support: It supports multiple programming languages, including Java, JavaScript, Python, etc., offering flexibility in the development environment.

  • Mocks: Playwright allows for the mocking of API requests, facilitating the writing of tests before the actual development of the API.

  • Documentation: It provides clear and comprehensive documentation supplemented with examples, making it easier to commence API testing.

  • Less Maintenance: The ability to incorporate multiple tests within a single framework significantly reduces the need for maintenance.

  • Reporters: Playwright offers various types of reporters, including HTML reporters, all available out of the box.


Since Playwright is an open-source tool, it is available at no cost. This makes it an accessible option for individuals and organizations looking to implement end-to-end test automation without incurring additional software costs.

Who′s It For?

Playwright is ideal for developers and test engineers who require a versatile testing framework that supports both end-to-end testing and API testing. Its support for multiple programming languages makes it suitable for teams with diverse development environments. However, due to its lack of a GUI and the necessity for strong technical knowledge to set up and utilize the framework effectively, it may not be the best fit for manual testers or those new to automated testing frameworks.

Why Should You Automate API Testing?

Manual API Testing involves maintaining a repository of test cases, where the Quality Assurance (QA) team manually verifies API test cases by sending HTTP requests and examining the responses, such as status codes and API contracts. This method enables a detailed, case-by-case inspection of each test, ensuring thorough testing. However, it is time-consuming and can potentially delay the release cycle due to its slower pace, posing a challenge in fast-paced development environments.

Automated API Testing utilizes tools to automate the testing process. These tools can often be integrated into the CI/CD pipeline, enhancing the efficiency of the release cycle. Significantly faster than manual testing, ideal for handling numerous test cases and iterations. It facilitates quicker code delivery by reducing QA/Dev dependency.

What To Look For In An API Testing Tool?

Selecting the right API testing tool ensures efficient and effective QA processes. Evaluating the tool against several critical factors is essential to finding the best fit for your project needs. Here are the condensed key points to consider:

  • CI/CD Integration: Compatibility with CI/CD pipelines for streamlined workflows.

  • Interoperability: Integrating easily with third-party tools (e.g., bug-tracking, product management).

  • Documentation: Provides comprehensive API documentation for ease of use.

  • Ease of Use: Features an intuitive interface accessible to technical and non-technical users.

  • Protocol Support: Support standard API protocols such as REST, SOAP, and GraphQL.

  • HTTP Request Support: Accommodates the majority of HTTP requests.

For a tool that meets these criteria and enhances your API testing process, consider exploring Testsigma. It′s designed to be accessible to all users and supports various API testing needs.