20 API Testing Tools – Beyond SOAP UI and Postman

We all know about API testing well. In my previous article – API testing, Key Terminologies and more……we learnt about the basics of API testing. Let’s now take a look on some of the API Testing tools.

To learn something new, I haven’t considered the leaders like SOAP UI, Postman, JMeter. Rather I have explored some tools which may be lesser known but have more or less same features and give a solid performance therefore worth giving a shot.


  • Zero code API Test Automation on Cloud.
  • Support for leading technologies.
  • API and UI Test Automation in the same simplified flow.
  • CI Driven regression suite executions.
  • Dynamic Environment management.
  • Directly correlate Business process and corresponding API for complete coverage.
  • API Test Case Management, Test Planning, Execution and tracking governance.
  • Trial – 14 days free trial

#2 API Fortress

  • API Fortress is a REST & SOAP API, Web Services, and Microservices testing platform.
     Out-of-the-Box Integrations.
  • Deploy On-Premises or in the Cloud.
  • Quickly Generate and Edit Functional Tests
    Detailed Reporting.
  • 30 days free trial

#3 API Science

  • API Science is an advanced API Monitoring service.
  • Monitor own APIs
  • Multi-step REST transactions
  • Advanced tests & validations
  • Get alerted on any issue
  • Run tests at any time
  • Monitor your own API & 3rd party APIs
  • Customized reporting
  • Intelligent API diagnostics
  • Collaborate using
  • team plans

#4 Apigee

  • Easily create API proxies and visually configure or code API policies as steps in the API flow.
  • Enforce consistent security best practices and governance policies across all APIs.
  • Publish APIs by providing reference documentation, manage the audience for an API from portal.
  • Analyze APIs, API traffic data, investigate traffic spikes, and trace live API calls.
  • Monitor APIs to ensure API availability.
    Publish APIs to a customizable portal, so that developers can easily explore, test, get API keys, and innovate fast.
  • 60 days free trial.

#5 Assertible

  • Can automatically sync API tests with the latest changes in the specification.
  • Integrates with the tools e.g. push code to GitHub or send alerts to Slack if failures happen.
  • Easily create tests for web service.
  • Continuously test multiple deployment and environment.
  • Set up scheduled monitoring to continuously test the services.
  • Run the same tests on multiple environments.
    Automatically execute post-deploy smoke tests.
  • HTTP assertions allow you to create domain specific test.

#6 Citrus Framework

  • Citrus is open source and licensed under Apache License 2.0.
  • Test automation by creating repeatable integration tests within continuous build.
  • Test complex messaging scenarios with step by step sequence of operations.
  • Use advanced logic in test cases including loops, delays, retries, parallel sections.
  • Json message payload validation.
  • JsonPath element validation.
  • Groovy Json validation.
    Simple test creation.
  • IDE support – execute tests as TestNG/JUnit tests from Eclipse, IntelliJ IDEA or NetBeans.


  • Development and test tool for REST web services and API applications.
  • Can display and validate the most common REST formats; XML, JSON, and HTML
  • Broad set of http properties.
  • Response data validation
    Simulate variations of input data or create global values for reuse across multiple API calls.
  • Enables to define chaining items of different types.
  • Support for data upload which enables users to post plain text data, contents of file, or mix of plain text data and disk files.
  • Free 30-day trial

#8 Insomnia

  • Free and open source on Mac, Windows, and Linux.
  • Reuse API keys or session IDs. Define environment variables globally or switch between sub-environments.
  • Generate http code for over thirty language libraries, including Curl, NodeJS, Go, Swift, Python, Java, C.
  • Free version available.

#9 Mockbin

  • Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
  • Mock custom endpoints using any HTTP Archive (HAR) response object.
    Test using your preferred language.
  • Mockbin accepts all standard Methods and allows method overriding in addition to Get and Post.
  • Mockbin supports output in JSON, YAML and XML, as well as an HTML.
  • Log and inspect incoming calls to your custom endpoints.

#10 Ping API

  • Ping-API is API testing allows to write test script in JavaScript and CoffeeScript.
  • It allows inspecting HTTP API call with a complete request and response data.
  • Can schedule test in every minutes or hour
    Support for writing script to set request headers, body and URL parameters.
  • It also supports validation of response headers and body.
  • Easy to generate test script with the input of API parameters.
  • Free for limited projects, varied pricing afterwards.

#11 Postwoman

Postwoman is an open-source API request builder. It helps you create your requests faster, saving you precious time on your development.

It also helps to create the requests faster, saving precious time on overall development.

  • Free, Open Sourced
  • Runs online
  • Self Hosted
  • Multi-platform & multi-device support
  • Progressive Web App
  • WebSocket testing
  • Customizations allowed
  • Pre-Request Scripts and environment variables setup
  • Docker support

#12 pyresttest

  • A REST testing and API microbenchmarking tool.
  • Tests are defined in basic YAML or JSON config files, no code needed.
  • Minimal dependencies (pycurl, pyyaml, optionally future), making it easy to deploy on-server for smoketests/healthchecks.
  • Supports generate/extract/validate mechanisms to create full test scenarios.
  • Returns exit codes on failure, to slot into automated configuration management/orchestration tools (also supplies parseable logs).
  • Logic is written and extensible in Python.
  • Return exit codes for failed results.
  • The building of test scenarios with generate/extract/validates mechanisms.
  • Easy deployment on the server.

#13 ReadyAPI

ReadyAPI is an integrated suite of API testing tools that includes:

  • SoapUI Pro (functional testing)
  • LoadUI Pro (performance testing)
  • ServiceV Pro (service virtualization)
  • Metrics & Data In One Place.
  • Create and maintain all the information relating to projects including test cases, data sources, and object components in one place for re-usability and management.
  • The entire ReadyAPI suite uses a central, standardized reporting function to support the measuring and displaying of data and metrics in real time.
  • Continuous Integration with ReadyAPI.
  • ReadyAPI provides many options for scripting to create functional, load, or security tests, using either Groovy or JavaScript.
  • With API Discovery, ReadyAPI will listen to live traffic of an API, recording responses and different interactions captured during the API activity.

#14 RestSharp

  • RestSharp is a popular HTTP client library for .NET.
    Featuring automatic serialization and deserialization, request and response type detection, variety of authentications.
  • JSON, XML and custom serialization and deserialization.
    Basic, OAuth 1, OAuth 2, JWT, NTLM are supported.
    HTTP call can be customized.
  • Send objects as the request body in JSON or XML, or as a form.

#15 SOAPSonar

  • SOAPSonar provides automated testing of each API independent of client, device or Consumer.
  • Automatically generating a UI to provide immediate feedback to developers, testers.
  • Validates each API independently, shortens the critical path and supports Agile development.
  • Fully automated, requires no scripting or maintenance thus reducing time and skill-set required.
  • Integration with variety test management software hence provides detailed progress reports.
  • Regression testing can be automated, providing early identification of changes to the API or versions.
  • Support for message and protocol layer identity standards allows for cloud testing.

#16 SOAtest

  • Broadest support for over 100 message formats and protocols.
  • With visual drag-and-drop tooling, users can create the most complex test scenarios without having to write a single line of code.
  • Test flow logic, complex assertions, looping, data driving, and keyword association, such as BDD with Cucumber, can all be easily built with minimal technical experience.
  • With its SMART API Test Generator plugin for Chrome, SOAtest monitors activity in your web UI from manual or exploratory testing and converts the behind-the-scenes API calls into meaningful API test scenarios.
  • Integration with existing CI/CD systems (i.e. Jenkins, TeamCity, Bamboo, Azure DevOps).
  • Collects REST and SOAP API coverage as part of test execution, reporting the test case coverage, missing or incomplete.

#17 TestMace

  • Creating and testing complex scenarios quickly.
  • Creating tests without actual programming.
  • Powerful autocomplete feature and highlighting of current variables values, functions etc.
  • A well-organized project structure and human-readable file format, which allow to store your project in the version control system repo and review tests and scenarios.
  • Advanced JS support in the built-in code editor, including the autocomplete feature and static analyzer.

#18 vRest

  • Record test cases by manually using your application once.
  • vrunner lets you execute your test cases just by running a command on your terminal.
  • Integration with Continuous Integration servers like Jenkins, TeamCity, Visual Studio Team Services etc. into vREST.
  • Automatically log issues into bug tracking systems like JIRA, Bugzilla, etc and notify team using Slack.
  • vREST lets you write test cases to validate your web/mobile application.
  • Supports Data driven testing. vREST lets you write test cases to validate your web/mobile application.
  • Schedule your test cases  using cronjob utility (in Mac or Linux) or Task Scheduler (in Windows).

#19 WebInject

  • WebInject is a free tool for automated testing of web applications and web services.
  • It can be used to test individual system components that have HTTP interfaces (JSP, ASP, CGI, PHP, AJAX, Servlets, HTML Forms, XML/SOAP Web Services, REST, etc).
  • Offers real-time results display and may also be used for monitoring system response times.
  • WebInject uses an XML API for defining and loading test cases. You can use WebInject without ever seeing its internal implementation.
  • Result reports are generated in HTML (for viewing) and XML 

#20 Paw

  • Paw is a full-featured HTTP client that lets you test and describe the APIs you build or consume.
  • It has a native macOS interface to compose requests, inspect server responses, generate client code and export API definitions.
  • Easily craft your HTTP requests, try and archive them.
  • Setup HTTP Headers, URL parameters, form-encoded POST key-values or text.
  • Get easy-to-read responses with well formatted headers and body.
  • Sync your projects with your team through Paw for Teams.
  • Simple request chaining (right-click in the UI, no code or globals).
  • Great workflow for when writing a fast-changing API


This list can go on and on however we have to stop somewhere. The above list is an effort to explore some different API testing tools which may not be the most popular ones but work well and perform effectively.

Though all API test tools listed above work well and are great options.however, there is no one-size-fit-all tool. There is no perfect tool for all organisations: Every organization has different requirements. 

So the key is – carefully considering the current and future project’s requirements and pros and cons of each solution.


I have been learning Software Testing since 12 years, have worked in multiple roles in Investment Banking, Aviation and Digital areas. Still exploring and learning, current article is also a part of this acquaintance. In case you would like to keep in touch, drop me a note at rahul@softwaretestingportal.com

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One thought on “20 API Testing Tools – Beyond SOAP UI and Postman

  1. Awesome! But there are other API testing tools that are simpler and no less efficient, such as ReqBin. With this tool, you can test your API by sending REST, SOAP, and HTTP API requests to the server right from your browser, and check the server responses. You can share and discuss your requests online; embed ReqBin widget with request examples on your website; see detailed request timings from different locations. Reqbin has built-in JSON, XML, HTML and CSS validators; 256-bit SSL encryption for all transmitted data.

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