SoapUI vs Postman vs Katalon Studio: API Testing Compared

SoapUI vs Postman vs Katalon Studio at a glance

Comparison as of November 2026, from each vendor's own site and docs.

Does Postman do SOAP?

Yes. Postman can send SOAP requests: you create an HTTP request, set the method to POST, put the SOAP envelope in a raw XML body, and add the SOAPAction header the service expects, as described in Postman's SOAP docs. The older claim that Postman handles only REST is out of date. Postman also has dedicated clients for GraphQL, gRPC, WebSocket, MQTT, and Kafka.

The difference is depth. Postman's SOAP docs have you write the envelope in a raw XML body, and Postman has also announced WSDL import that generates envelopes. SoapUI and ReadyAPI go further, with WSDL-driven projects, SOAP-specific assertions, and WS-Security. Katalon Studio sits between the two: it imports a WSDL and creates a SOAP request for each operation, then lets you run those requests in test cases with assertions.

SoapUI Open Source and ReadyAPI

SoapUI is two products from SmartBear, and comparisons often mix them up.

SoapUI Open Source is the free desktop tool. As of November 2026 the latest release is 5.10.0, and soapui.org lists support for REST, SOAP, GraphQL, and JMS, with test scripting in Groovy or JavaScript. It is a GUI application, and a command-line testrunner lets you execute projects without the interface and write JUnit-style reports that CI servers can read. soapui.org also lists what the free edition leaves out: built-in data-driven testing, automatic test refactoring when a spec changes, and native integrations with CI and lifecycle tools. Teams that need data loops in the free edition often script them in Groovy.

ReadyAPI is the commercial platform that replaced SoapUI Pro. ReadyAPI is sold as modules:

• API Functional Testing for REST, SOAP, Kafka, JDBC, and JMS, including security checks
• API Performance Testing for load, stress, and spike tests that reuse functional tests
• API Virtualization for mock services
• TestEngine for running SoapUI and ReadyAPI tests in parallel

ReadyAPI adds data-driven testing from Excel, CSV, and databases, reports in PDF, JUnit-style, XML, CSV, and Allure formats, a dashboard that compares runs, and CI plug-ins for Jenkins, TeamCity, and Azure DevOps. Scripts default to Groovy, with JavaScript as an option. It can also import Postman collections through a Postman plugin. SmartBear doesn't publish ReadyAPI prices; you configure a package and get a quote, and a free trial is available.

Where SoapUI fits: teams with heavy SOAP and WSDL estates, such as banking, insurance, and government integrations, and teams that want API performance testing and service virtualization from one vendor. For other options, see these SoapUI alternatives.

Postman

Postman started as a Chrome extension. That extension is retired, and as of November 2026 Postman runs as a desktop app on Windows, macOS, and Linux and as a web app. It is used across the API lifecycle: sending and debugging requests, organizing them into collections, documenting APIs, and sharing work in team workspaces.

For testing, Postman uses JavaScript. You write pre-request and post-response scripts to set variables and assert on responses, run whole collections in the Collection Runner (with a CSV or JSON data file on Solo and above), and run the same collections in CI with the Postman CLI. Postman's docs say the older Newman runner won't receive updates or fixes and can't run collections saved in the v12 format. Postman imports OpenAPI (including Swagger 2.0), AsyncAPI, Protobuf, GraphQL schemas, and cURL commands, works with collections stored in Git repositories, and offers a migration path for requests and environments from SoapUI, Insomnia, and other clients.

Pricing as of November 2026, from postman.com/pricing:

• Free: $0, 1 user
• Solo: $9 a month, billed annually, 1 user
• Team: $19 per user a month, billed annually
• Enterprise: contact sales

The plan change most teams notice: since March 2026 the Free plan covers a single user, so shared team workspaces need the Team plan ($19 per user a month, billed annually) or Enterprise. Where Postman fits: developers and testers who explore APIs by hand, share collections across a team, and want a fast path from a manual request to a scripted check.

Katalon Studio for API testing

Katalon Studio has a dedicated API and web service project type. In it you can:

• Send REST and SOAP requests, and send GraphQL queries as RESTful requests, with a keyword that validates a request body against a GraphQL schema. Studio's docs note that GraphQL variables aren't supported yet.
• Import Postman collections (format v2.1) as requests, and, from Studio 11.7.0, Postman environments as execution profiles
• Import REST requests from an OpenAPI or Swagger file, SOAP requests from a WSDL, and requests from SoapUI projects
• Build tests with built-in keywords in a low-code view, or switch to the script view and write Groovy or Java
• Drive requests with test data, verify responses with assertion keywords, and validate JSON responses against a JSON schema

The second reason teams pick Studio is scope. The same project can hold web and mobile tests, and Windows desktop tests on Professional and above, so a test case can create data through an API and then check it in the UI. For a step-by-step walkthrough, see API testing in Katalon Studio.

What each plan covers, as of November 2026 on katalon.com/pricing:

• Free: web, API, and mobile authoring with local runs, basic data sources, and report export
• Professional: $1,800 per seat per year (about $150 a month), billed annually. Adds parallel execution, BDD with Cucumber and Gherkin feature files, AI self-healing, JDBC data sources and data binding, Jira and Azure DevOps integrations, and headless and CI runs through the KRE add-on
• Enterprise: custom pricing, adding SSO, SCIM, audit logs, and private deployment options

For web and mobile tests, TestCloud (an add-on, Professional and above) runs suites on cloud browsers and devices; pure API suites don't need it. Studio results can upload to Katalon TestOps for reporting across runs. A 30-day free trial is available.

Key differences between SoapUI, Postman, and Katalon Studio

Protocol support

All three handle REST and SOAP. ReadyAPI covers the widest set of enterprise protocols (JMS, Kafka, JDBC, MQTT, XML-RPC, gRPC), and SoapUI Open Source covers REST, SOAP, GraphQL, and JMS. Postman has dedicated clients for GraphQL, gRPC, WebSocket, MQTT, and Kafka. Katalon Studio covers REST, SOAP, and GraphQL, which is the mix most web and mobile apps call.

Scripting language

This is where older comparisons go wrong: the three tools don't share a language. Postman scripts are JavaScript. SoapUI and ReadyAPI use Groovy or JavaScript. Katalon Studio uses Groovy and Java, with keywords for people who prefer not to code. If your team already writes Java or Groovy, SoapUI and Studio scripts will feel familiar; if your developers live in JavaScript, Postman will.

Moving tests between tools

Migration paths matter more than feature lists. ReadyAPI imports Postman collections through a plugin, and Postman can import requests and environments from SoapUI. Katalon Studio imports Postman collections and environments, OpenAPI and Swagger files, WSDLs, and SoapUI projects, so you can bring existing requests in rather than rebuilding them. Katalon Studio doesn't convert Postman pre-request or test scripts that set variables at run time, so plan time to port that logic.

Data-driven testing and BDD

SoapUI Open Source has no built-in data sources, so teams script loops in Groovy; ReadyAPI adds data-driven testing from Excel, CSV, and databases. Postman runs a collection once per row of a data file on Solo and above. Katalon Studio's Free plan reads test data from basic sources, and Professional and Enterprise add JDBC databases, multi-file combinations, and data binding at the test case and dynamic suite level. For behavior-driven development, Katalon Studio Professional and Enterprise run Cucumber and Gherkin feature files.

CI and reporting

The Postman CLI runs collections from the command line in common CI pipelines; Newman still exists but no longer gets updates. ReadyAPI has native plug-ins for Jenkins, TeamCity, and Azure DevOps, while SoapUI Open Source relies on its command-line testrunner and JUnit-style reports. Katalon Studio runs in Jenkins, GitHub Actions, Azure DevOps, and GitLab through Katalon Runtime Engine, an add-on for Professional and above. For reports, ReadyAPI has the widest export formats, and Studio results can go to Katalon TestOps for trends across runs.

API and UI tests in one place

SoapUI, ReadyAPI, and Postman test APIs only. If your regression suite also covers web or mobile flows, you would pair them with a UI tool and maintain two sets of tests. Katalon Studio keeps both in one project, which is its main advantage for QA teams and its main cost for teams that only test APIs.

Is SOAP better than REST API?

Neither is better in general; they suit different jobs. SOAP is a protocol with a strict XML contract (the WSDL) and built-in standards for security and reliable messaging, which is why it persists in banking, insurance, and government systems. REST is an architectural style that usually exchanges JSON over HTTP, is lighter to build and call, and is the default for public and mobile APIs. Most teams test both, which is why SOAP support still matters when you choose a tool.

Is Postman obsolete?

No. As of November 2026, Postman is actively sold in Free, Solo, Team, and Enterprise plans, supports more protocols than it did a few years ago, and works with collections stored in Git. What changed is the free tier: since March 2026 it covers 1 user, so team collaboration needs the Team plan or above. That change, plus cost per seat as teams grow, is why some teams compare alternatives rather than any decline in the tool itself.

How can you test APIs other than with Postman?

You have three broad options:

• Another API client such as Bruno, Insomnia, or Hoppscotch. Bruno and Insomnia also run scripted tests from a CLI (bru and inso), which suits teams that want a lighter Postman.
• An API testing tool such as SoapUI, ReadyAPI, or Katalon Studio, if you need assertions, data-driven runs, reports, and CI
• A code library such as REST Assured (Java) or Karate, if your developers want API tests in the same repository as the app

We compare these in detail in Postman alternatives for API testing. For a head-to-head on test automation, see Katalon Studio vs Postman.

Which API testing tool should you choose?

• Choose SoapUI Open Source if you test SOAP services, want WSDL-driven projects, and don't need built-in data sources or CI plug-ins. It costs nothing.
• Choose ReadyAPI if you need SOAP depth plus data-driven testing, performance tests, service virtualization, and broad report formats, and your budget allows a quoted enterprise license.
• Choose Postman if your team explores and documents APIs every day, writes JavaScript, and wants to share collections across developers and testers.
• Choose Katalon Studio if API tests need to run in the same suite as web, mobile, or desktop tests, if your team mixes low-code testers with Groovy or Java engineers, or if you want to bring Postman, OpenAPI, WSDL, and SoapUI assets into one place. Start on the Free plan and move to Professional when you need parallel runs, BDD, data binding, or CI.

Some teams combine them: Postman for exploration during development, and SoapUI, ReadyAPI, or Katalon Studio for the regression suite that gates a release.