SoapUI vs Postman for API Testing

Interested in comparing SoapUI vs Postman? Join us to dive into the main differences between these tools that are designed to cater to a broad spectrum of testing requirements, from straightforward requests to complex, automated test scenarios.

When we talk about tools for API testing, Postman and SoapUI come to mind almost immediately as they are known as the most powerful and recognized tools on the market.

In this article, we’ll dive into the essential features, the key differences from a tester’s perspective, and the practical applications of Postman and SoapUI, shedding light on how to leverage each of them in the realm of API testing.

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Introduction to SoapUI and Postman

SoapUI and Postman provide a wide array of features that cater to various testing needs. While both platforms extend their capabilities through paid versions, our journey today focuses on the rich functionalities available within their free offerings.

This exploration aims to equip you with a solid understanding of how each tool can be leveraged in API testing, boosting you to make the most out of these resources without initial investment. For enthusiasts eager to explore beyond the basics, we recommend visiting their websites.

SoapUI: An In-depth Look

Developed in Java, SoapUI is used for testing applications with Service Oriented Architecture (SOA) or REST. It supports a variety of protocols, including API protocols like SOAP and REST, along with HTTP, JMS, and JDBC for comprehensive service integration.

The tool has an open-source version and another paid version developed by SmartBear, primarily focused on enhancing your test results with advanced features. Notably, SoapUI supports SOAP API testing effectively, offering tools specifically designed to manage and automate SOAP-based services.

SoapUI was initially created to test SOAP services. Then it was extended to RESTful web services. 

For newcomers, it may present a medium-sized learning curve as it integrates several status codes and functionalities which may not always be intuitive.

Understanding SoapUI’s Structure

Soap UI’s work is organized into projects. The projects make up the workspace. A project can contain different types of tests, including functional tests, load tests, or mocks to isolate what you intend to test from necessary services (dependencies).

SoapUI offers two project formats: ‘Standalone Projects’ and ‘Composite Projects’, each capable of handling comprehensive security testing, performance testing, and API automation testing.

The ‘Standalone Projects’ are stored as a single XML file containing all the artifacts in the project. Compound projects allow multiple people to work collaboratively at the same time.

Project Types within SoapUI

SOAP Project

Created from a WSDL file or a specific request, these projects test all aspects of SOAP services including functional testing (also known as manual testing), automated testing, and load testing.

REST project

Initiating REST projects is possible either through a WADL file or by utilizing the URL and its parameters directly. These projects allow for the testing of RESTful services, the generation of multiple requests to examine the received information, and the exploration of numerous methods and operations, among other functionalities.

Generic project

Generic projects are multipurpose projects for services with varied interfaces and methods. They enable the combination of tests created for both REST and SOAP services, incorporating a data-driven testing approach, mocks, and all the functions that SoapUI offers.

This categorization indicates the main type of service tested. However, you can manually combine the service types in any project you create.

Postman: Simplifying API Testing

Postman is a tool that helps throughout the entire API development process but is mainly used for testing. Thanks to this tool, in addition to testing and invoking APIs, we will be able to monitor, document, simulate, and write automated tests for them.

While Postman provides extensive support for various API protocols, its collection and environment management features are designed to enhance only the REST API development process, streamlining testing and documentation specifically for REST (it was primarily designed for REST API testing).

It has a very easy-to-use and user-friendly interface, providing a robust platform to test APIs effectively.

It offers a large number of functionalities. For instance, it allows users to make any type of API call (REST, SOAP, or simply HTTP) and easily inspect the responses. Additionally, users can parse responses based on the response type (JSON, XML, or HTML).

You can find documentation on its official Webpage.

Unlike SoapUI, Postman works with API collections. These collections function as request groupers, which allows for the ordering of resources and services and testing each request in a quicker and easier way.

SoapUI vs. Postman: Understanding the Differences Between Them

Advantages of SoapUI       

• It’s a very complete application, with many functionalities, which can be a bit more complicated for what we need at times.
• It has better integration than Postman for working with the SOAP protocol (since it was initially intended for that), effectively supporting SOAP API testing. This showcases its superior capabilities for handling the Simple Object Access Protocol (SOAP).
• It’s a more mature project and has been on the market for longer.
• It’s an application that’s more oriented to comprehensive testing, including web service testing and API automation testing, not merely to invoke an API, document it, and publish it. It allows structuring the tests in test suites, test cases, and test steps, supporting a variety of testing needs.
• Test execution can be integrated with tools such as Maven and CI/CD engines.
• It allows you to add scripts in Groovy language, which means you can add validations, configure and/or automate tests.

Advantages of Postman

• Allows collaboration between team members.
• It has a more intuitive and attractive interface.
• It has an extension for Google Chrome, therefore it’s not necessary to install the desktop application.
• As we already mentioned in the description, it has a very interesting option, which is collections, which basically works as a database of requests.
• It’s extensible and can be integrated with other tools, for example by running the test suites from a CI/CD engine.
• It allows you to add scripts in Javascript language to add validations, configure and/or automate tests (this is done directly in the request).

Which to Choose to Get Started with API Testing?

If you’re about to start testing on API and you have little time, we would recommend Postman, since it requires less learning time. However, if what you are looking for is to put together a project in the medium or long term, we would recommend SoapUI as it offers more options and a better organization of the project.

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The Bottom Line

Postman and SoapUI stand out as the go-to choices for API testing, each bringing something unique to the table. Postman, with its intuitive interface, has quickly become a staple for developers looking to test, document, and share their APIs with ease, especially when working with REST APIs.

SoapUI, on the other hand, is the heavyweight when it comes to conducting more intricate testing, particularly for SOAP web services, thanks to its comprehensive testing features.

If you’re starting with API testing, or if you need to integrate detailed test scripts into a continuous testing environment, choosing the right tool depends on your specific needs and the types of APIs you are testing.

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