25 Best API Testing Tools

As the number of cloud apps and associated platforms has expanded, API testing has become increasingly vital. In basic terms, an API (Application Programming Interface) is the messenger that allows two software programs to interact and share data. Because there isn’t one, it’s a type of software testing that can’t be done on the front end. We’ve examined a few of the best free API testing tools in this article. So, continue reading!

25 Best API Testing Tools

As APIs become a vital aspect of software development, API testing is becoming increasingly crucial for developers and programmers. API testing cannot be done manually due to the nature of the API, hence we must use API test tools to test APIs. Read our compilation of the best API testing tools below.

1. Katalon Studio

Katalon Studio has been named the Gartner Peer Insights Customers’ Choices for Software Test Automation for three years in a row, making it the best api testing tools for API, Web, Mobile, and Windows applications.

• For projects of any size, it includes a straightforward user interface and productivity-enhancing features.
• Free API testing lessons and tool training are available at Katalon Academy.
• Katalon Studio is a comprehensive and robust API, Web, Desktop, and Mobile testing automation solution.
• Katalon Studio simplifies deployment by bundling all frameworks, ALM connections, and plugins into one package.
• Katalon Studio stands out among the best API testing tools for its ability to combine UI and API/Web services for many systems such as Windows, Mac OS, and Linux.
• Both automatic and exploratory testing is possible.
• In addition to being a free solution, Katalon Studio offers premium support services for small teams, businesses, and enterprises.
• Beginners and experts alike will benefit from the Manual and Scripting modes.
• Sample projects are offered for instant reference.
• Auto-completion, auto-formatting, and code inspection are all included in the code.
• Client certificates for REST, SOAP, and SSL are all supported.
• Swagger 2.0 and 3.0, Postman, WSDL, and WADL Native CI/CD connectors are all supported (Jenkins, Azure DevOps, CircleCI, Dockers, etc.).
• To create API test data, UI testing may be employed.
• To unify reports and activities, version control systems, CI/CD, test automation tools, and ALMs all include built-in reporting platforms.
• Code templates that may be customized.
• Its data-driven testing methodologies improve the coverage and reliability of tests.
• It includes AssertJ support for creating BDD-style fluent assertions.

2. ReadyAPI

The ReadyAPI platform from SmartBear allows you to test RESTful, SOAP, GraphQL, and other web services for functionality, security, and load. This is also one of best free API testing tools.

• ReadyAPI offers SoapUI, which starts at $659 per year, LoadUI Pro, which starts at $5999 per year, ServiceV Pro, which starts at $1199 per year, and ReadyAPI, which offers custom pricing.
• The Ready API is available for free for 14 days.
• It offers a smart assertion functionality that allows you to easily build assertions for hundreds of endpoints.
• You’ll be able to create thorough and data-driven functional API tests.
• ReadyAPI may be used in any situation.
• Git, Docker, Jenkins, Azure, and other services are all supported natively.
• For automated testing, it also offers a command-line interface.
• ReadyAPI also includes tools for removing dependencies during testing and development.
• It’s the best api testing tools for functional, security, and load testing RESTful, SOAP, GraphQL, and other web services.
• API functional testing, API performance testing, API security testing, and API and Web virtualization are all offered through a single platform.
• From start to finish, this platform will help you ensure the quality of all online services.
• It provides a range of customized automation methods for introducing API testing into your CI/CD process at each development step.
• It allows for the execution of functional tests and task queues in parallel.
• It has functions and tools for reusing functional tests and creating realistic load situations.
• DevOps and Agile Teams benefit the most from this platform.

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3. ACCELQ

ACCELQ is the first cloud-based continuous testing platform that automates API and web testing without writing a single line of code.

• ACCELQ assists IT teams of all sizes in accelerating their testing by automating critical lifecycle components such as test design, planning, development, and execution.
• API and UI Test Automation API governance encompass API test case administration, test preparation, execution, and tracking in the same simplified procedure.
• Clients of ACCELQ often save more than 70% of the cost of change and maintenance efforts in testing, addressing one of the industry’s most pressing issues.
• Planning a regression suite that includes requirements tracking and business process integration.
• Natural traceability with CI/CD and Jira/ALM integration.
• ACCELQ automates API testing with automated test design, codeless automation logic, complete test management, API regression planning, and 360 trackings.
• Managing a Dynamic Environment.
• For full end-to-end validation, use Chain API Tests.
• API Test suite modification effect analysis made simple and automated.
• For comprehensive coverage, directly correlate business processes and APIs.
• No vendor lock-in, open-source framework that may be extended.
• With an AI-powered core, ACCELQ may provide self-healing automation and other unique features.

4. Postman

Postman is another one of best free API testing tools for creating APIs. Collections, Workspaces, and Built-in Tools are the three sections of the Postman API Development Environment.

• A free plan is available for individuals and small groups. The Postman Pro plan, which is for a team of 50 workers, is the second option. It will cost $8 per month for each user. Postman Enterprise is the third plan, which may be utilized by any size team. The monthly fee for this plan is $18 per user.
• For whatever team size, it will allow you to share collections, create permissions, and manage participation in numerous workspaces.
• The formats Swagger and RAML (RESTful API Modeling Language) are supported.
• It offers a lot of features, is free, and has received a lot of great user reviews.
• With Postman collections, you can run requests, test and debug them, create automated tests and mock APIs, document them, and monitor them.
• ACCELQ’s continuous innovation process provides a heavy emphasis on design and user experience, with a persistent effort to expedite testing and improve offered Quality for its clients.
• Built-in tools will give the functionality that developers will need to operate with an API.
• It assists with automated testing.
• Aids in the exploratory testing process.
• It encourages team members to share their knowledge.
• The collaborative features of the Postman workspace will be available to you.
• Cloud API Test Automation with Zero Code.

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5. REST-Assured

REST-Assured simplifies REST service testing in the Java domain. It is one of best free API testing tools.

• It’s a free and open-source program.
• The Serenity automation framework is incorporated smoothly.
• Certain functionalities are pre-installed.
• REST-Assured accepts XML and JSON requests and responses.
• It supports the BDD Given/When/Then syntax.
• It is not essential to be an HTTP specialist to utilize the program.

6. Swagger.io

Swagger is a tool that will assist you throughout the full API lifetime.

• Swagger Hub comes in three types: free, team, and enterprise.
• The Team plan is $30 per month and includes two users. You may choose from 2, 5, 10, 15, and 20 users for this package. As the number of users grows, the price will rise. The Enterprise plan is the third option. The enterprise plan is for groups of 25 or more users. To learn more about this firm, contact it.
• This program will allow you to test APIs for functionality, performance, and security.
• LoadUI Pro is used for load and performance testing.
• It will allow you to reuse SoapUI’s functional tests. Many open-source tools are available through Swagger.
• Swagger Inspector assists developers and QAs in manually validating and exploring cloud APIs.

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7. JMeter

JMeter is open-source software for application load and performance testing.

• Its architecture is built on plugins. Jmeter is capable of generating test data.
• It’s cross-platform friendly. A protocol analyzer is Jmeter.
• As a unit test, developers may use this tool to test JDBC database connections.
• You’ll be able to use a range of programming languages with it.
• Jmeter also has configurable options and several different reports.
• This tool is perfect for load and performance testing of web applications.
• It has a command-line mode, which is useful for Java-compatible operating systems.
• Many different programs, servers, and protocols are loaded and performance tested.
• You may use it to playback test results.
• It supports variable parameterization as well as assertions.
• Per-thread cookies are supported.

8. Karate DSL

Karate DSL is an open-source API testing framework. The cucumber library serves as the foundation for the Karate framework.

• Intuit has published this tool that is specifically built for automated API testing.
• This tool allows a tester to build web service tests in a domain-specific language.
• However, a basic understanding of HTTP, JSON, XML, XPath, and JsonPath will be advantageous.
• It is possible to run many threads in parallel.
• It enables you to adjust settings.
• It allows you to create tests in any language that understands HTTP, JSON, or XML.
• programming language is not required to utilize this tool.
• Payload data can be reused for API testing.

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9. Airborne

Airborne is a free and open-source API testing framework.

• It’s an RSpec-driven Ruby framework.
• This utility has no user interface. It just gives a text file in which to write the code.
• It’s compatible with Rails-based APIs.
• To use this tool, you must have a basic understanding of Ruby and RSpec.
• It is compatible with Rack-based applications.

10. Pyresttest

Pyresttest is a python-based tool for RESTful API testing.

• It may also be used for micro-benchmarking.
• JSON config files are supported for testing. Python allows you to customize the tool.
• For unsuccessful results, return exit codes.
• The creation of test scenarios using technologies such as generate/extract/validate.
• It is simple to deploy on the server due to its minimum requirements, which is useful for smoke testing.
• No code is necessary.

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11. Apigee

Apigee is a platform for managing APIs across many clouds.

• Apigee has four price options: Free Evaluation, $500 per month for Team, $2500 per month for Business, and Enterprise for which you must contact them.
• A free trial is also included with the tool.
• The Business plan includes IP whitelisting, Java and Python callouts, and distributed traffic management.
• The Team plan includes API analytics, Web service callouts, and additional controls like security, mediation, and protocol.
• The Enterprise package includes additional security from Apigee Sense, a distributed network for low latency, monetization for new business models, and traffic isolation.
• For all APIs, provides security and governance policies. The utility makes it simple to construct API proxies using the open API definition.
• You can develop, protect, evaluate, and grow APIs from anywhere using this tool.
• It has a developer portal that may be customized.
• It works with Node.js.

12. RapidAPI

RapidAPI is the first tool on our list of the best API testing tools. A free trial is also included with the tool.

• The Business plan includes IP whitelisting, Java and Python callouts, and distributed traffic management.
• The Team plan includes API analytics, Web service callouts, and additional controls like security, mediation, and protocol.
• The Enterprise package includes additional security from Apigee Sense, a distributed network for low latency, monetization for new business models, and traffic isolation.

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13. SoapUI

SoapUI is a headless software solution dedicated entirely to API testing that allows you to run tests on SOAP APIs as well as web services REST.

• It is one of the most popular tools among testers since it allows them to design complicated scenarios and supports asynchronous testing.
• It also distinguishes out for its user-friendliness and superb data-driven testing.
• SoapUI comes with two bundles, one free and the other paid (the pro package).
• The free solution is easy to use, and testers may reuse scripts.
• With the pro package, it can also write custom code, extract data (from databases, files, and excels), and enable native CI/CD integrations.

14. Tricentis

Tricentis is a popular option for companies looking to incorporate Agile and DevOps practices.

• Pricing will vary depending on the features of each bundle.
• It employs model-based test automation, which simplifies script maintenance and facilitates regression testing.
• One of the most significant benefits is that it supports a wide range of protocols, including REST, SOAP, HTTP(s), MQ, JMS, NET TCP, IBM MQ, and others.
• Tricentis also provides end-to-end testing for mobile, cross-browser, and bundled apps, which is a significant advantage.

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15. Assertible

Assertible is widely regarded by developers and testers as one of the best api testing tools with a strong focus on dependability.

• It allows API tests at every stage from continuous integration through the delivery pipeline.
• Users will find Assertible to be highly handy.
• It’s compatible with GitHub, Zapier, and Slack.
• Additionally, Assertible uses readymade assertions to validate HTTP replies.
• There are three packages available for this API testing tool. The ordinary edition costs $25 per month; the startup plan is $50 per month; and the business plan, which costs $100 per month, is the most costly (and has the most features).
• Additionally, a free personal plan is available for running more manageable API tests and learning how Assertible works.

16. API Fortress (Now Sauce Labs)

API Fortress is another best free API testing tools. It simplifies the creation, execution, and automation of performance and functional testing.

• As a result, it’s the most comprehensive SOAP and REST monitoring solution on the market.
• The gadget is also noted for its ease of use.
• It also has one-click test integration and works with both physical and cloud hardware.
• The annual cost of API Fortress varies between $1,500 and $5,000. The amount that an organization is required to pay is also decided by the project’s specific criteria.
• API Fortress increases openness, which helps developers avoid redundancies and break down business silos.
• Its user interface is ideal for those with less technical knowledge.

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17. Hoppscotch

Hoppscotch, an open-source API testing tool that competes with the widely known Postman API testing tool, was the forerunner of Hoppscotch. The tool itself has a comprehensive collection of features that make testing easy. Here are a few noteworthy features.

• Liyas Thomas created the project, which he initially presented on Hackernoon.
• Hoppscotch advertises itself as a straightforward API testing tool with a simple user interface.
• Create a full-duplex communication channel over a single TCP connection.
• To send events, the stream server utilized an HTTP connection.
• You may transmit and receive data with a SocketIO server.
• Topics on the MQTT Broker can be subscribed to and published.
• Similar to Postman, you may access a history of previous inquiries, create collections for storing API requests, and set up a proxy to access restricted APIs.
• Hoppscotch is completely free to use, however, donations can be made via PayPal or Patreon.
• The project has changed its name and received over 26.000 ratings on GitHub after more than a year.

18. Testim

Testim is one of best free API testing tools. It is essentially a full-fledged test automation platform, with API testing as a component.

• You may then tailor the cost to your team’s requirements.
• Testim is unusual in that it uses artificial intelligence to help with test suite execution, maintenance, and even creation.
• This includes testing your API.
• For typical testing activities, you may also create API actions and validations.
• Testim, on the other hand, runs on a freemium model, making it simple to get started by gathering data from your API and immediately exercising the user interface.
• The major feature here is a framework that learns as you run and maintain your test suite.
• It’s a great approach to test the UI and API at the same time.

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19. Rest Console

The Rest Console application is a Google Chrome REST/HTTP Client that allows users to visually create and test custom HTTP requests with any RESTful API service.

• A simple user interface may be used to change custom headers.
• Allow users to add query parameters with ease.
• Plain, Basic, and OAuth are some of the authentication techniques that may be used with it.
• The user interface may be customized.
• Rest Console v4.0.2 has been updated to include several new features and bug fixes that will enhance the user experience (e.g., oAuth improvements, Collapsible sections, Clickable Links in Response, UI enhancements).
• Build a POST or PUT body from raw input.

20. Dredd

Dredd is another one of best free API testing tools. It is a command-line interface for testing APIs and documentation.

• It allows you to run ad-hoc tests using the name and URL of the API documentation.
• Dredd examines the API documentation and compares each response to the standards.
• As a consequence, it not only confirms the accuracy of the documentation but also puts the API to the test.
• Among the languages supported are PHP, Node.js, Python, Rust, Ruby, Perl, and Go.
• It’s easy to use and works with a wide range of programming languages.
• It validates APIs as well as their documentation.
• Hooks are also acceptable.

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21. Citrus

Citrus is a data format and communications protocol-based automated testing tool.

• It may assist you in automating integration testing for any messaging protocol or data type.
• HTTP, REST, JMS, and SOAP testing are all supported by Citrus.
• It provides robust XML message content validation features and allows complex testing logic to be written.
• Citrus is always there to help you meet your quality, function, and stability goals.
• The move from development to production is seamless.

22. Fiddler

Fiddler is a free web debugging proxy that may be used with any browser, operating system, or platform. This is also one of best free API testing tools.

• Fiddler allows you to track, modify, and reuse HTTP requests.
• It records network activity between the Internet and test PCs, which helps with online application debugging.
• The program is primarily used to monitor network traffic between a computer and the Internet.
• It is free to download and use, but corporate support costs money.
• Any internet browser, as well as any operating system or platform, may use the program.
• For more powerful add-ons, use the.NET programming language.
• Perfect for novice to experienced testers.

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23. RedwoodHQ

RedwoodHQ is an open-source SOAP/REST API testing tool. Java/Groovy, Python, and C# are among the languages it supports.

• It uses a web-based interface to allow several testers to run tests on the same application.
• For developers, this performance testing tool may be too shallow.
• It allows users to compare the results of each run.
• An open-source test automation framework.
• To automate any user interface, connect to open-source automation tools like Selenium, Appium, Silk4J, and others.

24. Appium

Appium is primarily used to test mobile applications, however, that does not imply it is restricted in its capabilities.

• It’s one of the open-source automated testing tools designed specifically for mobile apps.
• It can automate native, hybrid, and mobile web apps for iOS and Android.
• Appium has become one of the most popular and reliable mobile automated testing solutions.
• Because it uses the WebDriver API, it is straightforward to use for previous web test automation professionals.
• It’s open-source and free.
• It looks after the connection between Appium’s server and Xcode’s tools throughout execution.
• Java, Python, Ruby, C#, and more programming languages are supported.

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25. RoboHydra Server

RoboHydra Server is an excellent API testing solution for those who don’t have access to a server yet need one.

• It’s a tool for testing HTTP-based clients, or software that sends HTTP queries.
• User interfaces for mobile applications, public APIs, and Java-based systems are all supported.
• RoboHydra is a multifunctional robot.
• It allows clients-under-test to connect to it and execute tests.
• Any HTTP, HTTPS, or WebSockets client may be tested.
• It’s written in JavaScript and runs on Node.js.

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We hope that this guide was helpful and you could find best API testing tools. Let us know which method worked for you the best. Drop queries or suggestions in the comments section below.