The World's Most Widely Used Open Source API Testing Tool 

What is SoapUI?

SoapUI is the world's leading Functional Testing tool for SOAP and REST testing. With its easy-to-use graphical interface, and enterprise-class features, SoapUI allows you to easily and rapidly create and execute automated functional, regression, and load tests. In a single test environment, ReadyAPIvides complete test coverage - from SOAP and REST-based Web services, to JMS enterprise messaging layers, databases, Rich Internet Applications, and much more. And that's just the beginning.

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Why was SoapUI developed with an open source approach?

When SoapUI was initially created in 2006, there was no open source API testing tool on the market. The initial idea behind SoapUI was “Let’s get a lot of people to help!” – since then, developers have contributed code and provided valuable feedback, making SoapUI the product that it is today.

Because SoapUI is open source, usage and adoption spread quickly once it was launched. SoapUI is the most powerful open source SOAP and REST API testing tool and has benefitted from the vast numbers of testers and developers trying the product and spreading awareness of its functionality.

Without the open source community, SoapUI would not have the millions of users that it does today, making it the most widely used open source API tool for over 10 years.

Check out the video below of the creator of SoapUI, Ole Lensmar, talking about how SoapUI came to be and why it's such a special tool.

A Few of Our Favorite SoapUI Open Source Features

To see a complete list of features, please see the open source features page

Functional Testing

SoapUI is the Swiss-Army knife of automated Functional and Regression Testing. Powerful and innovative features help you validate and improve the quality of your services and applications. Best of all, you don't have to be a developer to write Functional Tests in SoapUI. Whether you're creating new TestSuites, adding TestCases, or adding assertions to your TestCases, it's simple and easy.

Drag and Drop Test Creation

Enhance your productivity with a code-free test environment. Create and run even the most complex test scenarios with drag and drop actions.

Complex Scenarios

Perform and validate a login procedure while testing your enterprise messaging and capturing client-server SOAP traffic. All at once!

Service Simulation (Mocking)

SoapUI MockServices let you mimic and create robust tests against SOAP and REST Web Services before they are implemented. They eliminate the expense of building full-scale replicas of your production systems and enable consumers to access the services without having to wait for them to be built or available. You can simulate any desired behavior, no matter how complex, and completely configure service responses.

Auto Mock Creation

SoapUI is loaded with enterprise-class features. It takes a WSDL from your desired location and automagically generates the MockService and its methods for you.

Custom Responses

Insert a Property Expansion in any element to fill it programatically, change the dispatch to specify different MockResponses to be sent out, and more.

Real Services

Mimic your Real Web Services without having to wait for them to be ready or accessible. Best of all, you don't have to build expensive full-scale replicas of your production systems.

Security Testing

Using a complement of tests and scans, protect your services on websites against the most common security vulnerabilities.

SQL Injection

Secure your database. Send in Malicious SQL statements in order to make sure it's not possible to get access to or weaken your databases.

XML Bomb

A document of extreme size can cause instability, make your systems inaccessible or make your system an attack vector. The XML Bomb scan will examine whether your system is vulnerable to stack overflows.

Load Testing

In SoapUI, you create advanced load tests quickly and easily on the base of existing functional API tests.

Click and Run Tests

Create load tests in SoapUI from existing functional tests with just a right-click.

Pre-Built Load Strategies

Select one of pre-defined load strategies - Simple, Fixed-Rate, Variable, or another - to simulate various test conditions easily.

Performance Validation

Use built-in assertions to check your web service performance and to ensure that it matches user expectations.

Technology Support

Building applications or services based on a variety of protocols? Loaded with advanced technologies, ReadyAPIvides support for all the common protocols and standards. So whether you want to test and deploy SOAP services or Flex/Flash web applications, SoapUI has got you covered.


SoapUI packs advanced end-to-end automation features, allowing you to dramatically reduce labor costs and improve your time-to-market. Using the Command-Line tools bundled with SoapUI, you can run your Functional/Load Tests and MockServices from just about any task scheduler, or as an integrated part of your build process. You can even customize the test execution to override test parameters, control what tests to run or output, and much more.


A big part of what makes SoapUI great is the universe of the open source community and partners around it, who have accelerated the pace of innovation on SoapUI. Another reason SoapUI is so great is that it allows anyone to develop their own set of SoapUI features as SoapUI Plugins. And ReadyAPI adds award-winning support from the SmartBear team.

Want Even More Features?

If you want even more great testing capabilities, download a free trial of ReadyAPI, or try out our complete API testing suite, ReadyAPI. ReadyAPI combines the power of ReadyAPI, ReadyAPI, ServiceV, and API Monitoring in AlertSite into a single application. From functional testing, to performance testing to post-deployment monitoring, SmartBear’s API tools help you to deliver accurate, fast, and secure APIs.

How can developers contribute to SoapUI?

Clone the SoapUI repository and inspect the source code locally.

See a missing feature? A bug? Code that you think could be improved? Anyone can be empowered to make changes to the source code and contribute them back to the project.

The SoapUI team has received numerous code contributions over the last several years – from bug fixes to additional features. SoapUI is nothing without the open source community, and we’re hugely thankful for the time and effort of our contributors.

No one knows APIs better than SmartBear. Find out what our Pro version of SoapUI can do to improve your testing.

Ready to join millions of users across the globe? Download SoapUI Today!

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