10 API Testing Tools You Can’t Live Without

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.

APIs play a key role in ensuring seamless interactions between various applications and services. With APIs being the backbone of modern software applications, robust testing is essential to guarantee their reliability, scalability, and security. That's when API testing tools come into play. From robust testing frameworks to intuitive interfaces, the below list of top 10 API testing tools is the backbone of modern software quality assurance.

Most of us know what API is. Here's a quick glimpse at API before we get into API testing. API stands for Application Programming Interface . API 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.

Read more - API vs UI Testing : Which One Should You Pick?

Types Of API Testing

There are several types of API testing, each serving a different purpose in ensuring the reliability and functionality of APIs. Here are some common types of API testing,

  • 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.

Types of API Testing

What Is An API Testing Tool?

An API testing tool is a test automation platform or framework designed to automate API testing. API testing tools like Testsigma provide a way to send requests to an API, receive responses, and validate that the API functions as expected.


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 has to manually verify API test cases, such as status codes, API contracts, etc., by sending HTTP requests. However, manual API testing is time-consuming and delays the release cycle.

Automated API testing is much faster than manual tests and is highly beneficial as it involves a large number of test cases and multiple iterations. Many API tools provide features to automate API testing. Some tools can be integrated into the 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.

Here, we will discuss the Top 10 best API testing tools.


10 Top API Testing Tools To Use

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

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.

Automate Your API Tests Along With Your UI Tests For Web, Mobile And Desktop Applications At The Same Place

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Testsigma API Testing tool

Key Benefits of Testsigma

Testsigma offers multiple benefits for automated API testing. Let's take a look at some of the key features offered by Testsigma,

  • Testsigma offers a simple and easy-to-use interface.

  • Automate your API tests 5x faster and ship products 10x faster.

  • It supports both codeless and code-based testing. This makes Testsigma a perfect tool that is accessible to both technical and non-technical users.

  • Automate your UI testing for web, mobile, and desktop apps, along with API tests in the same platform.

  • It fits perfectly in your DevOps and CI/CD pipeline.

  • You can test using different REST API methods like GET, POST, PUT, DELETE, and HEAD via an integrated or separate test for each method.

  • Testsigma API Testing tool
  • You can validate API responses with different comparison modes like strict, lenient, etc.

  • Automate API tests using low code, especially for response verification. Tools like Postman require you to write code in JavaScript for verification. Using Testsigma, you can verify by simply uploading the expected response.

  • Storing objects - supported via UI in Testsigma. Most other tools, like Postman, require you to write scripts to store objects.

  • You can do post plan hook actions. When you run an API test, based on the test results, you can perform custom actions (like rolling back the API configurations to a previous version, etc.)

Testsigma is the one-stop solution for all your test automation needs. With Testsigma, you can automate end-to-end testing of web, mobile, and desktop apps. Some of the testing types you can automate with this robust platform include

  • Cross-browser testing,

  • UI testing,

  • Integration testing,

  • Regression testing,

  • Visual testing,

  • Portability testing,

  • Compatibility testing, and more.

Automated API Testing with Testsigma

The video below demonstrates how Testsigma automates API testing.

Test Scenario - Validate user credentials

Automated API Testing with Testsigma -Demo
Pricing

Testsigma offers two pricing plans - Pro and Enterprise. Check the entire list of features that are part of each plan here. Also, you can sign up for a 21-day free trial loaded with all the features. Sign up and start automating your API tests in less than 2 minutes now.

Postman

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

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

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

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

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

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

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.

What to look for in an API Testing Tool?

When selecting an API testing tool, it's important to consider various factors to ensure that it meets your specific requirements. To help QA teams identify the right API testing tool for their project needs, look for these key indicators,

  • CI/CD Integration - Integration with CI/CD pipelines for seamless workflows.

  • Interoperable - Check if it can easily integrate with third-party tools like product management, CI/CD, bug-tracking, and collaboration tools.

  • Documentation - Proper API documentation to understand the platform and use it effectively.

  • Ease of Use - The tool should have an intuitive and user-friendly interface to make it easy for testers to create, manage, and execute API tests. Tools like Testsigma is a perfect fit as it is accessible to both technical and non-technical users.

  • Support for Different Protocols - Ensure the tool supports common API protocols like REST, SOAP, GraphQL, and others, depending on your specific API testing needs. Testsigma supports REST API and GraphQL testing.

  • Basic API Requirements - See if the tools support the majority of the HTTP requests.

Summary

Selecting the right API testing tool is crucial in ensuring seamless communication between software components. Take the time to evaluate and choose the API testing tool wisely. Embrace test automation, stay ahead of the curve, and continue to deliver high-quality software that meets and exceeds user expectations.

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