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  • Writer's pictureCraig Risi

The Pros and Cons of Different API Test Tools - SoapUI

Today I want to look at the next testing tool in my API testing tool series. And that tool is SoapUI. Postman might be one of the most widely used and popular API tools, but Soap is arguably one of the oldest and as a result, comes with a lot of dedicated users and an extensive list of features that have been developed over the years.

SoapUI does what it pretty much says as it serves as an interface for interacting with SOAP (Simple Object Access Protocol) and REST (Representational State Transfer) web services, though it can also interact with many other API protocols too. It is an open-source tool developed by SmartBear Software and was initially aimed toward the testing of SOAP API objects, but has adapted to support REST protocols as well, given their popularity in the development world.

Both tools offer a wide set of integration and collaboration features, while also offering both free and licensed versions of their tool offering – depending on the support required. SoapUI may have more collaboration functionality in its free version, but Postman offers a wider set of integrations across the board and works across the board with other testing tools more effortlessly.

I’ve designed to list down some of the major differences between the tools to make better sense of it. By doing this comparison, I’m not trying to single out that these are the only two options as I will be going through several more API testing tools in my evaluation – but given these are two of the biggest tools in the market, I thought I would provide it here.

Here's a comparison of Postman and SoapUI

1. User Interface and Usability:

Postman has a more modern and user-friendly interface. It is known for its simplicity and ease of use, making it accessible to both developers and non-technical users.

SoapUI has a more traditional interface, which some users might find a bit complex, especially if they are not familiar with web services and API testing.

2. Target Users:

Postman is designed for developers, testers, and other stakeholders who need to test APIs quickly and efficiently. It is often preferred for ad-hoc testing and exploratory testing.

SoapUI is targeted toward more experienced testers and QA professionals who need a comprehensive testing tool for SOAP, REST, and other web services. It offers more advanced features for in-depth testing scenarios.

3. Protocol Support:

Postman primarily focuses on RESTful APIs, although it can handle SOAP requests to some extent. Its strength lies in testing REST APIs with various HTTP methods and authentication mechanisms.

SoapUI is specialized in testing both SOAP and REST web services. It provides native support for SOAP-based services and can handle complex XML payloads and SOAP-specific features.

4. Test Creation:

Postman allows users to create tests using a JavaScript-based scripting language. Test scripts are written directly in the Postman interface, making it easy to add custom logic and validations to API requests and responses.

SoapUI offers a more diverse approach to test creation. Users can create tests using a graphical interface with drag-and-drop elements or opt for more advanced Groovy scripting for customization.

5. Data-Driven Testing:

Both tools support data-driven testing, but Postman's approach is more straightforward. Users can upload CSV or JSON files to feed data into their API requests.

In SoapUI, data-driven testing is also supported using external data sources, but it may require more configuration and setup compared to Postman.

6. Mocking:

Both Postman and SoapUI allow users to create mock APIs to simulate the behavior of backend services. However, SoapUI's mocking capabilities are often considered more robust and suitable for complex scenarios.

Understanding these core differences should help teams in deciding which tool might work best for them. In the end, though it will also fall to the types of APIs in use, as SoapUI does handle SOAP interfaces better and Postman does REST better. Familiarity with the JavaScript or Groovy programming language may also come into effect, though much like I mentioned in my article on Postman, you would likely be better off creating a framework of your independent of a tool for the best automation results.

A brief history of SoapUI

  • 2005: The initial version of SoapUI was created by Ole Lensmar, CTO and co-founder of Eviware Software, a Swedish software development company. It was developed as an internal tool to address the company's need for a more efficient way to test SOAP-based web services.

  • 2006: The first public release of SoapUI, version 1.0, became available. As an open-source project, it quickly gained traction in the developer community for its ease of use and powerful features for API testing.

  • 2007: With growing popularity and increased demand for more comprehensive API testing capabilities, Eviware Software released SoapUI Pro, a commercial version of the tool. The Pro version provided additional advanced features and support options to meet the needs of enterprise users.

  • 2009: SmartBear Software, a software tools and services company, acquired Eviware Software. Following the acquisition, development, and support for SoapUI continued under the new ownership.

  • 2012: The release of SoapUI 4.0 introduced several significant updates, including improved support for RESTful web services and enhanced scripting capabilities using Groovy.

  • 2015: SmartBear Software released SoapUI 5.0, which featured a redesigned user interface and introduced the concept of "TestSteps," making it easier to create and manage test cases.

Since then, SoapUI has been consistently updated and has a cloud offering as well, which offers a lot of different features. As a more mature tool, SoapUI offers a deeper set of features, though as it was designed more aimed towards developers than business end users, it is considered more difficult to use.

Below is a better look at its different pros and cons:


  • Ease of Use: SoapUI provides a user-friendly graphical interface, making it easy for testers to create, manage, and execute test cases without extensive coding knowledge.

  • Extensive Protocol Support: It supports both SOAP and REST web services, as well as other protocols like HTTP, JMS (Java Message Service), AMF (Action Message Format), etc.

  • WSDL and Swagger Integration: SoapUI can import WSDL files for SOAP services and Swagger (OpenAPI) specifications for RESTful services, simplifying the process of creating test cases.

  • Data-Driven Testing: SoapUI allows testers to perform data-driven testing by incorporating various data sets, enabling thorough testing of different scenarios.

  • Assertions: The tool offers a wide range of built-in assertions, allowing users to validate API responses and ensure they meet the expected criteria.

  • Security Testing: SoapUI supports testing API security features like adding security headers, handling authentication mechanisms, and evaluating potential vulnerabilities.

  • Mock Services: Testers can create mock services to simulate API behavior, facilitating testing when actual services are unavailable or still in development.

  • Integration with CI Tools: SoapUI can be easily integrated with Continuous Integration (CI) tools, enabling automated testing as part of the development and deployment process.

  • Scripting Support: Advanced users can leverage Groovy scripting to extend SoapUI's capabilities and perform more complex testing tasks.

  • Community and Support: As an open-source tool, SoapUI has a vibrant community, with numerous forums and resources available for help and guidance.


  • Learning Curve for Complex Scenarios: While the basic features are easy to use, handling more complex scenarios might require a deeper understanding of the tool and its functionalities.

  • Resource Intensive: Running tests on large-scale projects or with heavy data sets can be resource-intensive and may lead to performance issues.

  • Limited Performance Testing: While SoapUI can simulate multiple requests, it's not a specialized performance testing tool, so for extensive load and stress testing, dedicated performance testing tools might be more suitable.

  • Commercial Features in SoapUI Pro: Some advanced features are only available in the commercial version (SoapUI Pro), which might limit the capabilities of the open-source version.

  • Maintenance: As with any software, maintenance, and updates are essential to keep the tool functional and secure. Sometimes, outdated versions may have compatibility issues with newer technologies.

  • Steep Learning Curve for Advanced Scripting: While Groovy scripting offers powerful customization, it can be challenging for users without prior scripting experience.

  • Limited User Interface Customization: The interface may not provide extensive customization options, which could be a downside for users who prefer a more tailored experience.

Reasons to Select SoapUI

  • You are using a SOAP-based API protocol in your applications.

  • You have a technical testing team that is familiar with Groovy scripting.

  • You want to use an open-source tool but still want the benefit of a well-supported tool that offers a rich set of features.

SoapUI may be a little older and perhaps not look as shiny as the newer tools. But it has a strong technical feature set that can add a lot of value to an API testing team and if they don’t mind getting familiar with Groovy scripting, can help to address most automated testing solutions.


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