What it does
SoapUI Open Source is a desktop tool for testing web services and HTTP-based APIs, including SOAP and REST. A project can hold service requests and test cases; request steps send messages to a configured endpoint, while assertions compare the response with expected content or conditions. Its project tree and test-step model let API developers examine a service and turn selected requests into repeatable checks.
SoapUI's first REST project guide starts with an API endpoint or definition. From the project navigator, create a REST project, inspect a request and response, then add a test case and assertion for a result that matters to your API. The official example uses a sample Petstore service and verifies that a response contains expected text. In a real project, replace that sample with an endpoint you are allowed to test and choose assertions that reflect the contract your client depends on.
A test case can include multiple request steps. SoapUI's functional-testing guide describes validating response messages with assertions and chaining steps when a later request needs a value returned earlier. This makes the tool useful for service behavior checks and SOAP/WSDL workflows, but it does not provide the hosted API itself: you supply the service endpoint or definition, expected behavior, and any credentials or test data required by that service.
The open-source edition is free and licensed under EUPL 1.1 or later approved EUPL versions. SmartBear presents ReadyAPI as the related commercial suite for added capabilities such as security, performance, and virtualization testing; this entry is specifically SoapUI Open Source, not ReadyAPI or SoapUI Pro.
Strengths
- The REST project workflow can start from a service endpoint or API definition, then organize requests into test cases.
- Assertions can validate response content and response-time conditions; multiple request steps can be combined in one test case.
- Official downloads are provided for Windows, macOS, and Linux.
Watch out for
- SoapUI tests a service you provide; the user must supply an endpoint or definition and suitable expected outcomes and test data.
- SmartBear positions security, performance, and virtualization capabilities in its related ReadyAPI offering rather than the core SoapUI Open Source listing.
Best for
- Developers validating REST or SOAP API responses against expected fields, content, or response-time conditions
- Teams that want a desktop project containing repeatable service requests and functional test cases
Sources
- The World's Most Popular API Testing Tool | SoapUI (Oct 25, 2026)
- Getting Started With SoapUI (Oct 25, 2026)
- Your First REST Test (Oct 25, 2026)
- REST Functional Testing (Oct 25, 2026)
- Getting started with Assertions (Oct 25, 2026)
- SoapUI Latest Releases (Oct 25, 2026)
- SoapUI LICENSE.md (Oct 25, 2026)