SOAP UI vs Postman for API Testing: Which Should You Use?

Developers and Quality Assurance (QA) teams utilize many different API testing and validation tools to help them simplify the processes of testing, debugging, and validating APIs in the increasingly API-centric world of software development. Modern teams often combine End-to-End Testing with API-level testing to ensure full workflow reliability.

This article will compare SOAP UI to Postman regarding the function of API Testing, comparing the features of each product, and explaining their respective advantages in the context of current Continuous Integration/Continuous Delivery (CI/CD) pipelines. Near the end of the article, we will review how Keploy can enhance the functionality of both of these platforms by providing the ability to automate test creation and perform regression testing with ease.

What Is API Testing?

API Testing is a separate category of testing that verifies whether or not an Application Programming Interface (API) operates as it should according to the application. API Testing is in addition to any User Interface (UI) Testing and provides a method for validating that the logic of the system performs in the expected manner.

API Testing may have various types or categories; i.e., Functional Testing, Load Testing, Security Testing, etc. An effective API Testing tool enables a developer to maintain consistent quality, reliability, and rapid debugging capabilities throughout the services being tested.

What is SOAP UI?

SOAP UI is a tool for testing web services that are built using SOAP protocol. SOAP UI originally was designed only to support SOAP-based web services but has grown into a complete testing platform.

Typical use cases:

• Financial institutions or government APIs using SOAP/XML.

• Scenarios requiring security testing, load testing, or message-level validation.

• Teams needing data-driven or mocked test environments.

Key features of SOAP UI:

• Broad protocol support: SOAP, REST, JMS, JDBC, AMF.

• Groovy scripting for test customization.

• Built-in load and security testing modules.

• Assertions for message validation.

• Enterprise add-ons via ReadyAPI for advanced analytics.

What is Postman?

The postman started out on Chrome as an extension, but now it’s a full-featured desktop application for testing and developing RESTful APIs. Developers love this So Many Collaboration Features And An Easy-To-Use Interface

Typical use cases:

• Modern microservice architectures built on REST/GraphQL.

• Developer teams practicing CI/CD automation.

• Quick request testing, mocking, and documentation generation.

Key features of Postman:

• Simple, intuitive user interface.

• Collections for organizing API requests.

• Workspaces for team collaboration.

• Environment variables for dynamic testing.

• Native CI/CD integration and API documentation tools.

Comparing SOAP UI and Postman

let’s compare SOAP UI and Postman across key parameters

1. Protocol & API Support

The following items have been specified as supportable by the two items listed.

• SOAP UI has been created specifically for SOAP, but also provides support for REST, JMS, AMF, and JDBC. So if you have different protocols you need to work with, this would be a great choice.

• Postman is generally focused on REST and HTTP APIs. However, it can support SOAP with some configuration, but its primary feature set has a bias towards RESTful type architectures.

2. Ease of use and User Experience

• Postman has focused on users’ experience. The user-friendly interface provides an easy way to send requests and receive responses as well as manage variables without the use of any code.

• SOAP UI will allow for deeper control options for the experienced user, but there is a greater learning curve to use the product compared to Postman.

3. Automation & Integration

• SOAP UI integrates with build tools like Jenkins CI/CD systems, and it allows Groovy scripting for the purposes of automation – specifically for load testing and security testing.

• Postman is designed to work with current development workflows – It has native integrations to various CI/CD tools, GitHub Actions, Newman CLI, etc. and can also support automated regression testing within continuous integrations pipelines (CIP).

4. Collaboration & Team Workflows

• Postman is built for groups of users to work together – allows real-time access to workspaces in addition to providing version control for shared workspaces and role-based access control.

• SOAP UI has the potential to allow for collaborative efforts, but it is needed to have either the ReadyAPI edition of the product or rely on an external tool for collaboration -it is less intuitive for teams that are not in the same location.

5. Price, Performance & Environment

• SOAP UI is available in open-source as well as commercial (ReadyAPI) versions. The enterprise version has maximum reporting capability and best support, but also requires more resources than the open-source version.

• Postman is free for the individual and also for small teams, but has more integration capabilities and workspace features in the paid versions. Its light-weight feature makes it a daily-use tool for many.

6. When to Use Which

Choose SOAP UI if:

• You’re testing SOAP, legacy, or enterprise-grade APIs.

• You need security, load, or compliance testing.

• Your organization uses a complex tech stack with multiple protocols.

Choose Postman if:

• You work with REST or GraphQL APIs.

• You need rapid iteration and easy team collaboration.

• You’re integrating with CI/CD pipelines for automated testing.

Real-World Use Cases

Case 1: Banking APIs with SOAP UI
A Financial Services sector leverages SOAP UI as part of their process to ensure that secure SOAP-based transactions between external and internal systems are executed correctly. SOAP UI’s ability to perform security testing as well as its native WSDL support makes it a good solution for organisations who operate under compliance regulations.

Case 2: SaaS Startup with Postman
A Company which operates in SaaS and utilises a microservices architecture leverages Postman to manage and orchestrate all RESTful APIs. Developers use Newman to execute smoke tests following each deployment, which they have integrated into Continuous Integration (CI) pipelines, thus creating a process of continuous validation.

Case 3: Hybrid Teams Using Both
A number of teams will use Postman for functional validation before adding SOAP UI to test for load and security aspects, demonstrating that the two API testing tools can operate side by side based on the specific requirements of their teams.

How Keploy Fits In

While Postman and SOAP UI provide tools for scripting and manual testing of APIs, Keploy takes API testing to another level by allowing automatic creation of tests from actual usage.

By using real-time API traffic, Keploy creates structured test cases (input, output & mocks) which allow for repeatable regression testing.

How Keploy complements your existing setup:

• Integrates with Postman collections to record actual traffic as test cases.

• Eliminates flaky tests by validating consistency and data coverage.

• Works with any backend (REST, gRPC, databases) without changing code.

• Enables true shift-left testing by helping developers catch regressions early.

Whether you’re an experienced SOAP UI user or you’re a Postman pro, Keploy integrates seamlessly into your testing process and enables you to automate and speed up the quality assurance process.

Summary & Recommendation

Conclusion

SOAP UI and Postman are very dominant tools in their own right. If you have a large enterprise "architecture" with older systems or interfaces using multiple protocols, you probably want to go with SOAP UI. On the other hand, if you are developing APIs quickly and applying Continuous Integration and Continuous Delivery (CI/CD), as well as working collaboratively as a team, then Postman is going to be a better fit for you.

The right tool for your organisation comes down to your team’s level of expertise, Your API Architecture and how you’re looking to test. In any case, whether you decide on one tool or the other, we recommend looking at Keploy as a great tool to enhance your testing ecosystem by providing insight through capturing actual live usage of your systems and converting this information into repeatable automated test scripts.

FAQs

1. Does Postman support SOAP?
Yes, but its resources are limited. You can upload WSDL files and send SOAP Requests, but SOAP UI has many more advanced features than Postman.

2. Can I export tests between SOAP UI and Postman?
No, you cannot transfer tests directly between these two applications. If you want to transfer tests manually, you will need to re-create requests manually in either application, or use a third-party converter.

3. Which tool is better for load testing?
SOAP UI is designed with integrated Load & Security Testing capabilities, whereas Postman has primarily focused on Functional Integration Testing.

4. How can I integrate these tools into CI/CD?
You can easily integrate with CI/CD environments with Postman’s Newman or Postman CLI tools. You can integrate SOAP UI into CI/CD through automated Command (CLI) workflows, or utilize Jenkins as another means for Automating the Execution of the Tests.