The Best 10 API Testing Tools for Software Tester

API testing is a software testing practice that mainly focuses on determining if APIs meet expectations for functionality, reliability, performance, and security.

As APIs are becoming essential to software development, programmers must perform API tests. Unfortunately, this testing cannot be performed on the front end as there is no Graphic User Interface for APIs.

There are eight different types of API testing conducted:

  1. Validation testing helps verify the aspects of an API’s product, behavior, and efficiency. It plays an essential role in the development process.
  2. Functional testing – Functional testing tests specific functions of the API.
  3. UI testing – UI testing helps you test user interface performance for the API and integral parts of API.
  4. Security Testing – Security testing helps secure your API against all external threats and risks.
  5. Load Testing is conducted after a specific unit, or the whole codebase is completed. Load testing monitors the software performance at both average and peak situations.
  6. Runtime and error detection – This testing type allows you to detect execution errors, resource leaks, and software bugs.
  7. Penetration Testing – Penetration testing help you to detect vulnerabilities and security loopholes in your APIs.
  8. Fuzz Testing – To test the API performance and detect coding errors and bugs, the API testing tool randomly sends a massive amount of data to the API test subject to make it crash.

Where is API testing Performed?

There are three different layers involved in the software development process. The user interface, business, and database layers are used for modeling and manipulating data. API testing is mainly performed at the middle layer, the business layer, in which business logic processing is carried out, and all transactions between the user interface and database layers happen.

What are the Benefits of API Testing?

API Testing allows access to and test application without any user interface. It will help you test the application’s code-level functionality before running GUI tests.

  1. Language-Independent – Testing data is exchanged via XML and JSON formats so that any language supports test automation. In addition, both Formats are structured data, making the verification fast and stable.
  2. GUI Independent – It can be performed in the app before GUI testing. It gives your better feedback and improves team productivity before GUI testing.
  3. Faster Releases – API testing allows you to speed up your app development compared to UI testing. It means faster software development to release software.

Below, we’ve analyzed 10 API testing tools, outlining their features.

Best API Testing Tools for Software Testers

1 RapidAPI – the world’s largest API marketplace

RapidAPI - world's largest API marketplace

RapidAPI’s Enterprise Hub is an internal API Marketplace customized to match your company’s brand, integrates seamlessly with internal systems and tooling, supports all of your APIs, and is deployed as a cloud-based service, on-premises, and across multi-cloud environments. RapidAPI provides a unified experience across the API development lifecycle, from designing and developing APIs with RapidAPI Design by Paw to testing and monitoring them with RapidAPI Testing. Using RapidAPI, developers can search and test the APIs, subscribe, and connect to the APIs — all with a single account, single API key, and single SDK.


  1. world’s largest API Marketplace
  2. Easy to manage APIs in a single dashboard
  3. Speed up in software development process
  4. improved User interface and Mobile friendly

Visit: RapidAPI

2 Test Mace – Best API Testing Tools

Test Mace - Best API Testing Tools

Test Mace is a modern, powerful cross-platform tool for working with an API and creating automated API tests. The testing tool provides everything you usually see in your favorite development tools. With just a single click, the developer can perform complete regression testing. In addition, a simple and convenient user interface allows you to build complex scenarios.


  1. Creating and testing complex scenarios quickly
  2. testing without actual programming
  3. Powerful variables Mechanism
  4. A well-organized project structure and human-readable file format allow you to store your project in the version control system repo and review tests and scenarios.
  5. Authentication
  6. Quickly share your scenarios with teammates.
  7. Autocomplete
  8. Syntax Highlighting

Visit: Test Mace

3 Postman – Collaboration platform for API Development

Postman - Collaboration platform for API Development

Postman is a collaboration platform for API testing and development. It simplifies each level of software development and streamlines collaboration so you can create better APIs instantly. Postman gives you a simple, intuitive client interface to manage your API data via Postman’s desktop, web, CLI, and API interfaces.


  1. Collaborative Platform for API development
  2. API first development
  3. Quickly and easily send REST, SOAP, and GraphQL requests directly within Postman.
  4. Automate manual tests and integrate them into your CI/CD pipeline to ensure that any code changes won’t break the production API.
  5. Communicate the expected behavior by simulating endpoints and their responses without having to set up a backend server.
  6. Generate and publish beautiful, machine-readable documentation to make your API easier to consume.
  7. Stay up-to-date on the health of your API by checking performance and response times at scheduled intervals.
  8. Provide a shared context for building and consuming APIs and collaborate in real-time with built-in version control.

Visit: Postman

4 Tricentis Tosca – AI-based software testing tool

Tricentis Tosca - AI-based software testing tool

Tosca is a continuous testing platform to automate end-to-end testing for software applications develop by Tricentis software company. The testing tool uses a scriptless, AI-based, no-code approach for end-to-end test automation. It is only a testing solution to provide model-based test automation.


  1. Automated and manual testing
  2. Browser-based performance testing
  3. The Most Comprehensive Support for SAP UIs & Technologies
  4. The continuous testing platform accelerates testing with a script-less, AI-based, no-code approach for end-to-end test automation ranging from API to UI, databases to BI solutions programming languages to packaged applications.
  5. Model-based test automation helps you to avoid script maintenance.
  6. Automation Recording Assistant (ARA) by Tricentis provides an intuitive record and playback experience that turns anyone into a test automation specialist.
  7. Orchestrated Service Virtualization (OSV) by Tricentis allows business users to build virtual services directly from their API test modules without deep technical or coding knowledge.
  8. Tricentis TDM (Test Data Management) reduces test data creation time by automatically creating and provisioning on-demand synthetic or masked production data for test automation.

Visit: Tricentis Tosa

5 SOAP UI – Best API Testing Tools

SOAP UI - Best API Testing Tools

SoapUI is the world’s most widely-used open-source automated testing tool for SOAP and REST APIs. Write, run, integrate, and automate advanced API Tests with ease. Its user-friendly interface and enterprise-class features allow you to quickly and rapidly create and execute automated functional, regression, and load tests.


  1. Point-and-click and Drag-and-drop features make it easy to create tests quickly.
  2. The API testing tool is built entirely on the java platform and uses Swing for the user interface.
  3. Multi-platform
  4. Provide support for IDEA, Eclipse, and NetBeans.
  5. Test SOAP and REST web services, JMS, AMF, and make any HTTP(S) and JDBC calls.

Visit: SOAP UI

6 Apigee – API Testing Tools and predictive analytic Tool

Apigee - API Testing Tools and predictive analytic Tool

Apigee is an API management and predictive analytic tool to design secure and scale APIs. It allows users to measure and test API performance, supports, and build API using editors like Swagger.


  1. Highly scalable and secure API management platform
  2. Fast and adjustable caching
  3. Quick jumpstart
  4. predictive analytics to ensure intelligent and customized interactions.
  5. Connect devices to the Internet, enabling partners and developers to access device functionality and data with APIs.
  6. Protect your apps from cyber threats and bad bots with data-driven enterprise-grade API security.
  7. AI-powered API monitoring
  8. Manage microservices as APIs
  9. Multi-layer security and privacy
  10. Identify performance issues by tracking API traffic, response times, and error rates

Visit: Apigee

7 vREST – Automated REST API testing tool

vREST - Automated REST API testing tool

vREST is an automated REST API testing tool. It is a straightforward extension that records the web applications’ HTTP requests under test. Also, it documents their parameters, headers, and responses, and it will automatically store them as test cases in vREST.


  1. API validation and automation
  2. A simple and intuitive tool to quickly validate your REST APIs.
  3. Validate Builds by integrating vREST with CI/CD servers like Jenkins, TeamCity, Azure DevOps, Travis CI, etc.
  4. monitor and analyze your APIs health
  5. Complete data control on your Test Data.
  6. vREST NG stores Test Data locally and creates a directory containing the necessary files and folders for each project.
  7. Works in Hosted Mode

Visit: vREST

8 JMeter – API Testing Tools by Apache

JMeter - API Testing Tools by Apache

JMeter is an open-source java-based load testing tool for analyzing and measuring the performance and load test static and dynamic web applications. It can simulate a heavy load on a server, group of servers, network, or object to test its strength or analyze overall performance under different load types.


  1. Load, perform, measure, and analyze many different applications/server/protocol types.
  2. A fully-featured IDE helps you plan, record, build, and debug.
  3. Command-line mode helps you to load tests from any platform.
  4. Complete portability and 100% Java Purity
  5. Full multithreading framework
  6. Caching and offline analysis/replaying of test results.
  7. highly extensible core
  8. A complete and ready-to-present dynamic HTML report.
  9. Live reporting into 3rd party databases like InfluxDB or Graphite.
  10. Easy correlation through extracting data from the most popular response formats, HTML, JSON, XML, or any textual format.

Visit: JMeter

9 Assertible – Testing and Monitoring Tool for Websites and APIs

Assertible - Testing and Monitoring Tool for Websites and APIs

Assertible is a testing and monitoring tool for websites and APIs, focusing on three goals: Easily create robust and meaningful assertions for your web app. Monitor your web services and notify you and your team when things aren’t working as expected.


  1. Reliable test and monitor your Web services.
  2. Stay in Sync with your updated specification.
  3. It is directly linked with your favorite tools to build a dependable web application monitoring workflow that gives you control of your tests and alerts.
  4. Reduce bugs in web applications by using Assertible to create an automated QA pipeline that helps you catch failures & ship code faster.
  5. Run the same tests on all environments.
  6. Validate your app after every deployment.
  7. Assertible’s powerful and robust HTTP assertions allow you to create domain-specific tests, so you’ll be the first to know when something goes wrong.

Visit: Assertible

10 RestSharp – Open Source HTTP Client Library for ASP.NET

RestSharp - Open Source HTTP Client Library for ASP.NET

RestSharp is an open-source HTTP client library that makes it easy to utilize RESTful services. It provides a developer-friendly UI to work with RESTful services while separating the internal intricacies of working with HTTP requests. RestSharp supports both synchronous and asynchronous requests.


  1. REST Client Framework for all .NET Platforms.
  2. Async friendly. All operations use async, await keywords.
  3. Integrates with Polly’s resilience and transient-fault-handling.
  4. Automatic serialization with any method (JSON, Binary, SOAP, Google Protocol Buffers).
  5. Installation from NuGet is accessible on any platform.
  6. Uses strong types with the content body.
  7. Supports WebAssembly, Android, iOS, Windows 10, .NET Framework 4.5+, .NET Core.
  8. Supports GET, POST, PUT, PATCH, and DELETE with the ability to use less common HTTP methods.

Visit: RestSharp

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